Human sleep cycles and dream times, what influences the timing and intensity? Sleep history included

I'm doing sleep and dreams research and have developed an iPhone application to help me track my bedtime, rise time, sleep onset and also mark dreams. The app also monitors overall activity overnight as an Actigraph, recording periods of elevated motion and inactivity.

I have a lot of sleep cycle data that I have trouble analyzing.

I know that circadian rhythm is at play with 90-110 minute sleep cycles ehxibited over the course of the night, each one is a progression of various sleep stages, from NREM to REM. REM is more likely to result in a dream reported if awakened during REM.

What I'm seeing is a bunch of orderly patterns, and a lot of chaotic behavior that I cannot explain. Particularly the times of going to sleep and awakening, while dreams exhibit more orderly behavior, with dreams reported at similar times on subsequent days.

I'm also interested in any insight as to what's causing me to wake up at certain times and report dreams. What could be involved in this kind of behavior? I saw research about deuretic hormones not being suppressed for the night, causing the urge to urinate to awaken the dreamer.

Right now I have 90 days of sleep onset and dream data that looks like this:

Complete 90 day sleep history

  1. In this case, each black marker indicates the sleep onset time for the night
  2. The orange marker indicates the time of getting out of bed
  3. The green markers are dreams that I report upon awakening from a
    dream, so dreams occur prior to the marker's location.

  4. Each green
    marker's brightness indicates more clear dream content remembered and recorded.

  5. Cyan markers are lucid dreams, where I was aware that I was dreaming within a dream.
  6. Cyan color of a marker indicates that I could control the dream's content from within a dream.
  7. Red markers are periods of insomnia.
  8. The cyan line is number of hours after bedtime
  9. The purple line is sleep cycle approximation (90 minutes).

The data is stacked with each row being a day of data. You will notice that your eyes start to automatically seek patterns within the vertical arrangement of markers. Because each marker is a dream reported upon awakening, they roughly trace the sleep cycles over the course of the night.

I'm interested in learning what influences the desire to go to bed at a particular time? What influences the getting out of bed times? is there some sort of analysis I can perform to understand the pattern within the sleep cycles as it evolves over multiple nights?

Any input is appreciated!

I'm interested in learning what influences the desire to go to bed at a particular time? What influences the getting out of bed times?

It is the circadian rhythm. Circadian rhythm is mediated by the suprachiasmatic nucleus of hypothalamus, which gets afferent nerves from optic nerve. So, the circadian rhythm is mediated by light. Initiation of the NREM Stage 1 sleep is controlled by the lateral preoptic nucleus, which is another area in the hypothalamus, so it is mainly the absence of light which starts sleep.

I'm also interested in any insight as to what's causing me to wake up at certain times and report dreams.

Sleep is not equal to absence of consciousness, it is just an diminished state of consciousness. Sleep consist of mainly 4 stages, NREM-1, NREM-2, NREM-3 and REM. Every stage, the "depth" of sleep, or the level of the decrease in your consciousness changes. REM is the stage in which dreaming most frequently occurs, and also it is the sleep stage where your consciousness is highest, so you are more likely to awake because of the stimulus coming from the environment.

Human sleep cycles and dream times, what influences the timing and intensity? Sleep history included - Biology

Collectively the daily, seasonal, lunar and tidal geophysical cycles regulate much of the temporal biology of life on Earth. The increasing isolation of human societies from these geophysical cycles, as a result of improved living conditions, high-quality nutrition and 24/7 working practices, have led many to believe that human biology functions independently of them. Yet recent studies have highlighted the dominant role that our circadian clock plays in the organisation of 24 hour patterns of behaviour and physiology. Preferred wake and sleep times are to a large extent driven by an endogenous temporal program that uses sunlight as an entraining cue. The alarm clock can drive human activity rhythms but has little direct effect on our endogenous 24 hour physiology. In many situations, our biology and our society appear to be in serious opposition, and the damaging consequences to our health under these circumstances are increasingly recognised. The seasons dominate the lives of non-equatorial species, and until recently, they also had a marked influence on much of human biology. Despite human isolation from seasonal changes in temperature, food and photoperiod in the industrialised nations, the seasons still appear to have a small, but significant, impact upon when individuals are born and many aspects of health. The seasonal changes that modulate our biology, and how these factors might interact with the social and metabolic status of the individual to drive seasonal effects, are still poorly understood. Lunar cycles had, and continue to have, an influence upon human culture, though despite a persistent belief that our mental health and other behaviours are modulated by the phase of the moon, there is no solid evidence that human biology is in any way regulated by the lunar cycle.

Wish Fulfillment? No. But Dreams Do Have Meaning


Dreams may not be the secret window into the frustrated desires of the unconscious that Sigmund Freud first posited in 1899, but growing evidence suggests that dreams — and, more so, sleep — are powerfully connected to the processing of human emotions.

According to new research presented last week at the annual meeting of the Associated Professional Sleep Societies in Seattle, adequate sleep may underpin our ability to understand complex emotions properly in waking life. "Sleep essentially is resetting the magnetic north of your emotional compass," says Matthew Walker, director of the Sleep and Neuroimaging Lab at the University of California, Berkeley. (See the top 10 scientific discoveries of 2008.)

A recent study by Walker and his colleagues examined how rest — specifically, rapid eye movement (REM) sleep — influences our ability to read emotions in other people's faces. In the small analysis of 36 adults, volunteers were asked to interpret the facial expressions of people in photographs, following either a 60- or 90-minute nap during the day or with no nap. Participants who had reached REM sleep (when dreaming most frequently occurs) during their nap were better able to identify expressions of positive emotions like happiness in other people, compared with participants who did not achieve REM sleep or did not nap at all. Those volunteers were more sensitive to negative expressions, including anger and fear.

Past research by Walker and colleagues at Harvard Medical School, which was published in the journal Current Biology, found that in people who were sleep deprived, activity in the prefrontal lobe — a region of the brain involved in controlling emotion — was significantly diminished. He suggests that a similar response may be occurring in the nap-deprived volunteers, albeit to a lesser extent, and that it may have its roots in evolution. "If you're walking through the jungle and you're tired, it might benefit you more to be hypersensitive to negative things," he says. The idea is that with little mental energy to spare, you're emotionally more attuned to things that are likely to be the most threatening in the immediate moment. Inversely, when you're well rested, you may be more sensitive to positive emotions, which could benefit long-term survival, he suggests: "If it's getting food, if it's getting some kind of reward, finding a wife — those things are pretty good to pick up on." (See more about sleep.)

Our daily existence is largely influenced by our ability "to understand our societal interactions, to understand someone else's emotional state of mind, to understand the expression on their face," says Ninad Gujar, a senior research scientist at Walker's lab and lead author of the study, which was recently submitted for publication. "These are the most fundamental processes guiding our personal and professional lives."

REM sleep appears to not only improve our ability to identify positive emotions in others it may also round out the sharp angles of our own emotional experiences. Walker suggests that one function of REM sleep — dreaming, in particular — is to allow the brain to sift through that day's events, process any negative emotion attached to them, then strip it away from the memories. He likens the process to applying a "nocturnal soothing balm." REM sleep, he says, "tries to ameliorate the sharp emotional chips and dents that life gives you along the way." (See the top 10 medical breakthroughs of 2008.)

"It's not that you've forgotten. You haven't," he says. "It's a memory of an emotional episode, but it's no longer emotional itself."

That palliative safety-valve quality of sleep may be hampered when we fail to reach REM sleep or when REM sleep is disrupted, Walker says. "If you don't let go of the emotion, what results is a constant state of anxiety," he says.

The theory is consistent with new research conducted by Rebecca Bernert, a doctoral candidate in clinical psychology at Florida State University who specializes in the relationship between sleep and suicidal thoughts and behaviors, and who also presented her work at the sleep conference this week.

In her study of 82 men and women between the ages of 18 and 66 who were admitted into a mental-health hospital for emergency psychiatric evaluation, Bernert discovered that the presence of severe and frequent nightmares or insomnia was a strong predictor of suicidal thoughts and behaviors. More than half of the study participants had attempted suicide at least once in the past, and the 17% of the study group who had made an attempt within the previous month had dramatically higher scores in nightmare frequency and intensity than the rest. Bernert found that the relationship between nightmares or insomnia and suicide persisted, even when researchers controlled for other factors like depression. See TIME's special report on how not to get sick.)

Past studies have also established a link between chronic sleep disruption and suicide. Sleep complaints, which include nightmares, insomnia and other sleep disturbances, are listed in the current Substance Abuse and Mental Health Services Administration's inventory of suicide-prevention warning signs. Yet what distinguishes Bernert's research is that when nightmares and insomnia were evaluated separately, nightmares were independently predictive of suicidal behavior. "It may be that nightmares present a unique risk for suicidal symptoms, which may have to do with the way we process emotion within dreams," Bernert says.

If that's the case, it may help explain the recurring nightmares that characterize psychiatric conditions like posttraumatic stress disorder (PTSD), Walker says. "The brain has not stripped away the emotional rind from that experience memory," he says, so "the next night, the brain offers this up, and it fails again, and it starts to sound like a broken record . What you hear [PTSD] patients describing is, 'I can't get over the event.' "

At the biological level, Walker explains, the "emotional rind" translates to sympathetic nervous-system activity during sleep: faster heart rate and the release of stress chemicals. Understanding why nightmares recur and how REM sleep facilitates emotional processing — or hinders it, when nightmares take place and perpetuate the physical stress symptoms — may eventually provide clues to effective treatments of painful mental disorders. Perhaps, even, by simply addressing sleeping habits, doctors could potentially interrupt the emotional cycle that can lead to suicide. "There is an opportunity for prevention," Bernert says.

The new findings highlight what researchers are increasingly recognizing as a two-way relationship between psychiatric disorders and disrupted sleep. "Modern medicine and psychiatry have consistently thought that psychological disorders seem to have co-occuring sleep problems and that it's the disorder perpetuating the sleep problems," says Walker. "Is it possible that, in fact, it's the sleep disruption contributing to the psychiatric disorder?"

How Does Human Sleep Compare With the Sleep of Other Animals?

It’s not only the required amount of sleep that varies among humans and other animals. Sleep cycles and processes that take place during sleep can also differ. These differences in sleep habits and needs are caused by many factors, including brain size, diet, body mass index (BMI), and social hierarchy. Predatory animals usually sleep in longer uninterrupted periods that are diurnal—primarily at night, like humans—or nocturnal—primarily during the daytime, like tigers.

REM Sleep in Humans and Animals

What happens while humans sleep? During sleep, our bodies cycle through four stages. Physical changes take place during each stage, such as decreased temperature and heart rate. Different types of brain activity also occur during each stage, with more activity taking place during the fourth stage, called rapid-eye movement (REM) sleep. In addition to the fluttering eyes behind eyelids, this sleep phase is also characterized by muscle twitching and waking-like electrical brain patterns (electroencephalogram or EEG). Although humans can dream during any phase of sleep, they are most likely to during REM sleep.

Do all animals have REM sleep? Many terrestrial mammals, including primates, and some reptiles, birds, and aquatic invertebrates experience REM sleep. The amount of REM sleep varies widely depending on the species. Because elephants sleep so little, REM sleep doesn’t happen daily for them. In contrast, house cats can spend up to 8 hours a day in REM sleep.

Some animals, such as dolphins and whales, do not show typical behaviors associated with REM sleep. However, whales do exhibit some muscle jerking that might be representative of REM sleep.

The cycles of REM sleep vary across species, too. Humans experience REM sleep approximately every 90–120 minutes during sleep, while mice experience REM sleep every 10–15 minutes.

The Brain During Sleep in Humans and Animals

Animals obtain their sleep and rest in a multitude of ways. In contrast to humans, some animals only have one hemisphere of the brain sleep at a time. For example, in dolphins, it appears that only one half of the brain exhibits sleep characteristics while the other exhibits wakeful characteristics. This allows them to swim to the water’s surface to breathe in while sleeping.

Lack of Sleep in Humans and Animals

Without enough sleep, humans are susceptible to changes in mood, impaired memory, illness, and even death. These risks are true for many animals as well, such as rats. Rats that are sleep-deprived quickly lose weight and develop infections. After just a few weeks without proper sleep, rats die.

How Does Human Sleep Compare To Other Primate Sleep?

In a study of 30 types of primates, humans slept the least over a 24-hour period. One hypothesis explaining why humans sleep less than other primates is that in the past, humans faced increased pressures of survival, risks of being preyed upon, and benefits of social interaction. These experiences likely impacted current sleep practices. Today, humans have shorter, deeper sleep with more REM cycles than other primates. Human sleep is described as “more efficient” than the sleep of primates.

One clear commonality among primates is nest making, or, in the case of humans, bed making. Nest building is present across great ape species, though shapes, sizes, and locations of nests vary. Because of the prevalence of nest building, it is hypothesized that the last common ancestor between humans and other primates was a nest builder. While primate nests may have once been used primarily for feeding, they evolved into spaces of rest that promote better sleep. It’s also hypothesized that ground sleeping made human ancestors more vulnerable, so sleeping periods had to become shorter.

What does it mean when we dream?

Dreams are stories and images that our minds create while we sleep. They can be entertaining, fun, romantic, disturbing, frightening, and sometimes bizarre.

They are an enduring source of mystery for scientists and psychological doctors. Why do dreams occur? What causes them? Can we control them? What do they mean?

This article will explore the current theories, causes, and applications of dreaming.

Dreams: Do they represent our unconsious desires?

There are several theories about why we dream. Are dreams merely part of the sleep cycle, or do they serve some other purpose?

Possible explanations include:

  • representing unconscious desires and wishes
  • interpreting random signals from the brain and body during sleep
  • consolidating and processing information gathered during the day
  • working as a form of psychotherapy

From evidence and new research methodologies, researchers have speculated that dreaming serves the following functions:

  • offline memory reprocessing, in which the brain consolidates learning and memory tasks and supports and records waking consciousness
  • preparing for possible future threats
  • cognitive simulation of real life experiences, as dreaming is a subsystem of the waking default network, the part of the mind active during daydreaming
  • helping develop cognitive capabilities
  • reflecting unconscious mental function in a psychoanalytic way
  • a unique state of consciousness that incorporates experience of the present, processing of the past, and preparation for the future
  • a psychological space where overwhelming, contradictory, or highly complex notions can be brought together by the dreaming ego, notions that would be unsettling while awake, serving the need for psychological balance and equilibrium

Much that remains unknown about dreams. They are by nature difficult to study in a laboratory, but technology and new research techniques may help improve our understanding of dreams.

Phases of sleep

Dreams most likely happen during REM sleep.

There are five phases of sleep in a sleep cycle:

Stage 1: Light sleep, slow eye movement, and reduced muscle activity. This stage forms 4 to 5 percent of total sleep.

Stage 2: Eye movement stops and brain waves become slower, with occasional bursts of rapid waves called sleep spindles. This stage forms 45 to 55 percent of total sleep.

Stage 3: Extremely slow brain waves called delta waves begin to appear, interspersed with smaller, faster waves. This accounts for 4 to 6 percent of total sleep.

Stage 4: The brain produces delta waves almost exclusively. It is difficult to wake someone during stages 3 and 4, which together are called “deep sleep.” There is no eye movement or muscle activity. People awakened while in deep sleep do not adjust immediately and often feel disoriented for several minutes after waking up. This forms 12 to 15 percent of total sleep.

Stage 5: This stage is known as rapid eye movement (REM). Breathing becomes more rapid, irregular, and shallow, eyes jerk rapidly in various directions, and limb muscles become temporarily paralyzed. Heart rate increases, blood pressure rises, and males develop penile erections. When people awaken during REM sleep, they often describe bizarre and illogical tales. These are dreams. This stage accounts for 20 to 25 percent of total sleep time.

Neuroscience offers explanations linked to the rapid eye movement (REM) phase of sleep as a likely candidate for the cause of dreaming.

Dreams are a universal human experience that can be described as a state of consciousness characterized by sensory, cognitive and emotional occurrences during sleep.

The dreamer has reduced control over the content, visual images and activation of the memory.

There is no cognitive state that has been as extensively studied and yet as frequently misunderstood as dreaming.

There are significant differences between the neuroscientific and psychoanalytic approaches to dream analysis.

Neuroscientists are interested in the structures involved in dream production, dream organization, and narratability. However, psychoanalysis concentrates on the meaning of dreams and placing them in the context of relationships in the history of the dreamer.

Reports of dreams tend to be full of emotional and vivid experiences that contain themes, concerns, dream figures, and objects that correspond closely to waking life.

These elements create a novel “reality” out of seemingly nothing, producing an experience with a lifelike timeframe and connections.


Nightmares are distressing dreams that cause the dreamer to feel a number of disturbing emotions. Common reactions to a nightmare include fear and anxiety.

They can occur in both adults and children, and causes include:

Lucid dreams

Lucid dreaming is the dreamer is aware that they are dreaming. They may have some control over their dream.

This measure of control can vary between lucid dreams. They often occur in the middle of a regular dream when the sleeping person realizes suddenly that they are dreaming.

Some people experience lucid dreaming at random, while others have reported being able to increase their capacity to control their dreams.

What goes through our minds just before we fall asleep could affect the content of our dreams.

For example, during exam time, students may dream about course content. People in a relationship may dream of their partner. Web developers may see programming code.

These circumstantial observations suggest that elements from the everyday re-emerge in dream-like imagery during the transition from wakefulness to sleep.


Studies have examined the “characters” that appear in dream reports and how they the dreamer identifies them.

  • Forty-eight percent of characters represented a named person known to the dreamer.
  • Thirty-five percent of characters were identified by their social role (for example, policeman) or relationship to dreamer (such as a friend).
  • Sixteen percent were not recognized
  • Thirty-two percent were identified by appearance
  • Twenty-one percent were identified by behavior
  • Forty-five percent were identified by face
  • Forty-four percent were identified by “just knowing”

Elements of bizarreness were reported in 14 percent of named and generic characters.

Another study investigated the relationship between dream emotion and dream character identification.

Affection and joy were commonly associated with known characters and were used to identify them even when these emotional attributes were inconsistent with those of the waking state.

The findings suggest that the dorsolateral prefrontal cortex, associated with short-term memory, is less active in the dreaming brain than during waking life, while the paleocortical and subcortical limbic areas are more active.


The concept of ‘repression’ dates back to Freud. Freud maintained that undesirable memories could become suppressed in the mind. Dreams ease repression by allowing these memories to be reinstated.

A study showed that sleep does not help people forget unwanted memories. Instead, REM sleep might even counteract the voluntary suppression of memories, making them more accessible for retrieval.

Two types of temporal effects characterize the incorporation of memories into dreams:

  • the day-residue effect, involving immediate incorporations of events from the preceding day
  • the dream-lag effect, involving incorporations delayed by about a week
  • processing memories into dream incorporation takes a cycle of around 7 days
  • these processes help further the functions of socio-emotional adaptation and memory consolidation

Dream lag

Dream-lag is when the images, experiences, or people that emerge in dreams are images, experiences, or people you have seen recently, perhaps the previous day or a week before.

The idea is that certain types of experiences take a week to become encoded into long-term memory, and some of the images from the consolidation process will appear in a dream.

Events experienced while awake are said to feature in 1 to 2 percent of dream reports, although 65 percent of dream reports reflect aspects of recent waking life experiences.

The dream-lag effect has been reported in dreams that occur at the REM stage but not those that occur at stage 2.

Memory types and dreaming

Two types of memory can form the basis of a dream.

  • autobiographical memories, or long-lasting memories about the self
  • episodic memories, which are memories about specific episodes or events

A study exploring different types of memory within dream content among 32 participants found the following:

  • One dream (0.5 percent) contained an episodic memory.
  • Most dreams in the study (80 percent) contained low to moderate incorporations of autobiographical memory features.

Researchers suggest that memories of personal experiences are experienced fragmentarily and selectively during dreaming. The purpose may be to integrate these memories into the long-lasting autobiographical memory.

A hypothesis stating that dreams reflect waking-life experiences is supported by studies investigating the dreams of psychiatric patients and patients with sleep disorders. In short, their daytime symptoms and problems are reflected in their dreams.

In 1900, Freud described a category of dreams known as “biographical dreams.” These reflect the historical experience of being an infant without the typical defensive function. Many authors agree that some traumatic dreams perform a function of recovery.

One paper hypothesizes that the main aspect of traumatic dreams is to communicate an experience that the dreamer has in the dream but does not understand. This can help an individual reconstruct and come to terms with past trauma.


The themes of dreams can be linked to the suppression of unwanted thoughts and, as a result, an increased occurrence of that suppressed thought in dreams.

Fifteen good sleepers were asked to suppress an unwanted thought 5 minutes prior to sleep.

The results demonstrate that there were increased dreams about the unwanted thought and a tendency to have more distressing dreams. They also imply that thought suppression may lead to significantly increased mental disorder symptoms.

Research has indicated that external stimuli presented during sleep can affect the emotional content of dreams.

For example, the positively-toned stimulus of roses in one study yielded more positively themed dreams, whereas the negative stimulus of rotten eggs was followed by more negatively themed dreams.

Typical dreams are defined as dreams similar to those reported by a high percentage of dreamers.

Up to now, the frequencies of typical dream themes have been studied with questionnaires. These have indicated that a rank order of 55 typical dream themes has been stable over different sample populations.

Some themes are familiar to many people, such as flying, falling, and arriving late.

The 55 themes identified are:

  • school, teachers, and studying
  • being chased or pursued
  • sexual experiences
  • falling
  • arriving too late
  • a living person being dead
  • a person now dead being alive
  • flying or soaring through the air
  • failing an examination
  • being on the verge of falling
  • being frozen with fright
  • being physically attacked
  • being nude
  • eating delicious food
  • swimming
  • being locked up
  • insects or spiders
  • being killed
  • losing teeth
  • being tied up, restrained, or unable to move
  • being inappropriately dressed
  • being a child again
  • trying to complete a task successfully
  • being unable to find toilet, or embarrassment about losing one
  • discovering a new room at home
  • having superior knowledge or mental ability
  • losing control of a vehicle
  • fire
  • wild, violent beasts
  • seeing a face very close to you
  • snakes
  • having magical powers
  • vividly sensing, but not necessarily seeing or hearing, a presence in the room
  • finding money
  • floods or tidal waves
  • killing someone
  • seeing yourself as dead
  • being half-awake and paralyzed in bed
  • people behaving in a menacing way
  • seeing yourself in a mirror
  • being a member of the opposite sex
  • being smothered, unable to breathe
  • encountering God in some form
  • seeing a flying object crash
  • earthquakes
  • seeing an angel
  • part animal, part human creatures
  • tornadoes or strong winds
  • being at the movie
  • seeing extra-terrestrials
  • traveling to another planet
  • being an animal
  • seeing a UFO
  • someone having an abortion
  • being an object

Some dream themes appear to change over time.

For example, from 1956 to 2000, there was an increase in the percentage of people who reported flying in dreams. This could reflect the increase in air travel.

What do they mean?

Relationships: Some have hypothesized that one cluster of typical dreams, including being an object in danger, falling, or being chased, is related to interpersonal conflicts.

Sexual concepts: Another cluster that includes flying, sexual experiences, finding money, and eating delicious food is associated with libidinal and sexual motivations.

Fear of embarrassment: A third group, containing dreams that involve being nude, failing an examination, arriving too late, losing teeth, and being inappropriately dressed, is associated with social concerns and a fear of embarrassment.

Brain activity and dream types

In neuroimaging studies of brain activity during REM sleep, scientists found that the distribution of brain activity might also be linked to specific dream features.

Several bizarre features of normal dreams have similarities with well-known neuropsychological syndromes that occur after brain damage, such as delusional misidentifications for faces and places.

Dreams and the senses

Dreams were evaluated in people experiencing different types of headache. Results showed people with migraine had increased frequency of dreams involving taste and smell.

This may suggest that the role of some cerebral structures, such as amygdala and hypothalamus, are involved in migraine mechanisms as well as in the biology of sleep and dreaming.

Music in dreams is rarely studied in scientific literature. However, in a study of 35 professional musicians and 30 non-musicians, the musicians experienced twice as many dreams featuring music, when compared with non-musicians.

Musical dream frequency was related to the age of commencement of musical instruction but not to the daily load of musical activity. Nearly half of the recalled music was non-standard, suggesting that original music can be created in dreams.

It has been shown that realistic, localized painful sensations can be experienced in dreams, either through direct incorporation or from memories of pain. However, the frequency of pain dreams in healthy subjects is low.

In one study, 28 non-ventilated burn victims were interviewed for 5 consecutive mornings during their first week of hospitalization.

  • Thirty-nine percent of people reported pain dreams.
  • Of those experiencing pain dreams, 30 percent of their total dreams were pain-related.
  • Patients with pain dreams showed evidence of reduced sleep, more nightmares, higher intake of anxiolytic medication, and higher scores on the Impact of Event Scale.
  • Patients with pain dreams also had a tendency to report more intense pain during therapeutic procedures.

More than half did not report pain dreams. However, these results could suggest that pain dreams occur at a greater frequency in populations currently experiencing pain than in normal volunteers.


One study has linked frontotemporal gamma EEG activity to conscious awareness in dreams.

The study found that current stimulation in the lower gamma band during REM sleep influences on-going brain activity and induces self-reflective awareness in dreams.

Researchers concluded that higher order consciousness is related to oscillations around 25 and 40 Hz.


Recent research has demonstrated parallels between styles of romantic attachment and general dream content.

Assessment results from 61 student participants in committed dating relationships of six months duration or longer revealed a significant association between relationship-specific attachment security and the degree to which dreams about romantic partners followed.

The findings illuminate our understanding of mental representations with regards to specific attachment figures.

Death in dreams

Researchers compared the dream content of different groups of people in a psychiatric facility. Participants in one group had been admitted after attempting to take their own lives.

Their dreams of this group were compared with those of three control groups in the facility who had experienced:

    and thoughts about suicide
  • depression without thinking about suicide
  • carrying out a violent act without suicide

Those who had considered or attempted suicide or carried out violence had were more likely to have dreams with content relating to death and destructive violence. One factor affecting this was the severity of an individual’s depression.

Left and right side of the brain

The right and left hemispheres of the brain seem to contribute in different ways to a dream formation.

Researchers of one study concluded that the left hemisphere seems to provide dream origin while the right hemisphere provides dream vividness, figurativeness and affective activation level.

A study of adolescents aged 10 to 17 years found that those who were left-handed were more likely to experience lucid dreams and to remember dreams within other dreams.

Studies of brain activity suggest that most people over the age of 10 years dream between 4 and 6 times each night, but some people rarely remember dreaming.

It is often said that 5 minutes after a dream, people have forgotten 50 percent of its content, increasing to 90 percent another 5 minutes later.

Most dreams are entirely forgotten by the time someone wakes up, but it is not known precisely why dreams are so hard to remember.

Steps that may help improve dream recall, include:

  • waking up naturally and not with an alarm
  • focusing on the dream as much as possible upon waking
  • writing down as much about the dream as possible upon waking
  • making recording dreams a routine

Who remembers their dreams?

There are factors that can potentially influence who remembers their dreams, how much of the dream remains intact, and how vivid it is.

Age: Over time, a person is likely to experience changes in sleep timing, structure, and electroencephalographic (EEG) activity.

Evidence suggests that dream recall progressively decreases from the beginning of adulthood, but not in older age. Dream also become less intense. This evolution occurs faster in men than women, with gender differences in the content of dreams.

Gender: A study of dreams experienced by 108 males and 110 females found no differences between the amount of aggression, friendliness, sexuality, male characters, weapons, or clothes that feature in the content.

However, the dreams of females featured a higher number of family members, babies, children, and indoor settings than those of males.

Sleep disorders: Dream recall is heightened in patients with insomnia, and their dreams reflect the stress associated with their condition. The dreams of people with narcolepsy may a more bizarre and negative tone.

Dream recall and well-being

One study looked at whether dream recall and dream content would reflect the social relationships of the person who is dreaming.

College student volunteers were assessed on measures of attachment, dream recall, dream content, and other psychological measures.

Participants who were classified as “high” on an “insecure attachment” scale were significantly more likely to:

  • report a dream
  • dream frequently
  • experience intense images that contextualize strong emotions in their dreams

Older volunteers whose attachment style was classed as “preoccupied” were significantly more likely to:

Dream recall was lowest for the “avoidant” subjects and highest for the “preoccupied” subjects.

Which Is Most Important: Diet, Exercise, or Sleep?

While trying to manage a busy, hectic life, it’s understandable to want to prioritize activities that provide the most benefit. Unfortunately, diet, exercise, and sleep are so deeply intertwined, it’s not possible to say that one is more important than the others.

For people who are tight on time or aren’t able to tackle all three, it can be helpful to talk to a doctor for personalized recommendations. A doctor, with knowledge about someone’s unique health history, can help to prioritize lifestyle changes. Doctors can also refer their patients to specialists, like nutritionists, dieticians, physical therapists, and sleep specialists for more tailored advice.

Neuroscience Approach

The neuroscientific approach is all about the biological process of humans (Feldman, R. p. 19). The focus is on how neurons fire within the body and the brain. This is a relatively new approach to psychology, but not necessary to dreaming. Some experts believe the Freud&aposs psychodynamic approach to dreaming was based on the available information about the brain during his time.

The theory is the idea of activation-synthesis. This theory holds the idea that REM sleep triggers memories that are lodged somewhere in the brain. Random electrical impulses and firing during sleep, trigger the brain to remember certain memories ( Feldman, p. 147). This theory was developed by psychiatrist J. Allan Hobson, and he theorized that the human brain needs to make sense of the world, even during sleep, and uses random memories to create a logical storyline.

According to Hobson and his original model, dreams are not unconscious wishes but instead a part of biology and the neurons that fire in the brain stem during sleep (van den Daele, L., 1996). In Hobson&aposs view, dreams are meaningless and are only present because the brain and body are still functioning while a person is sleeping. Many other researchers and psychologists have built and expanded Hobson&aposs original theory. However, it still is the basis for the neurological explanation of dreams.

The five stages of sleep are critical for understanding dream psychology.

The Science of Dreaming: 9 Key Points

The most important findings of scientific dream research can be summarized in nine key points. Many important questions remain unanswered, but these nine findings have solid empirical evidence to support them.

1. Rapid eye movement (REM) sleep is a trigger for dreaming, but is not identical with dreaming.

All mammals have sleep cycles in which their brains pass through various stages of REM and non-REM sleep. Dreaming seems to occur most often, and most intensely, in REM sleep, a time when many of the brain’s neuroelectrical systems have risen to peak levels of activation, as high as levels found in waking consciousness. However, dreaming occurs outside of REM sleep, too REM sleep is neither necessary nor sufficient for dreaming.

2. REM helps the brain grow.

The fact that REM sleep ratios are at their highest early in childhood (newborns spend up to 80 percent of their sleep in REM, whereas adults usually have 20 to 25 percent of their sleep in REM) suggests that REM, and perhaps dreaming, have a role in neural maturation and psychological development.

3. Dreaming also occurs during hypnogogic, hypnopompic, and non-REM stage 2 phases of sleep.

In the transitional times when a person is falling asleep (hypnogogic) or waking up (hypnopompic), various kinds of dream experiences can occur. The same is true during the end of a normal night’s sleep cycle, when a person’s brain is alternating exclusively between REM and non-REM stage 2 phases of sleep, with a relatively high degree of brain activation throughout. Dreams from REM and non-REM stage 2 are difficult to distinguish at these times.

4. The neuroanatomical profile of REM sleep supports the experience of intense visionary imagery in dreaming.

During REM sleep, when most but not all dreaming occurs, the human brain shifts into a different mode of regional activation. Areas of the prefrontal cortex involved in focused attention and rational thought become less active, while areas in the limbic system (involved in emotional processing, memory, and instinctive responses) and the occipital lobe (involved in visual imagination) become much more active. This suggests that the human brain is not only capable of generating intense visionary experiences in dreaming, it has also been primed to do so on a regular basis.

5. The recurrent patterns of dream content are often continuous with people’s concerns, activities, and beliefs in waking life.

This is known as the “continuity hypothesis," and it highlights the deep consistency of waking and dreaming modes of thought. People’s dreams tend to reflect the people and things they most care about in the waking world. A great deal of dream content involves familiar people, places, and activities in the individual’s waking life. The dreaming imagination is fully capable of portraying normal, realistic scenarios. This means dreaming is clearly not a process characterized by total incoherence, irrationality, or bizarreness.

6. The discontinuities of dreaming — when things happen that do not correspond to normal waking life — can signal the emergence of metaphorical insights.

Research on the improbable, unreal, and extraordinary elements of dream content has shown that, on closer analysis, this material often has a figurative or metaphorical relationship to the dreamer’s waking life. Metaphorical themes and images in dreams have a long history in the realm of art and creativity, and current scientific research highlights the dynamic, unpredictable nature of dreaming as an endless generator of conceptual novelty and innovation.

7. Dream recall is variable.

Most people remember one to two dreams per week, although the memories often fade quickly if the dreams are not recorded in a journal. On average, younger people tend to remember more dreams than older people, and women more than men. Even people who rarely remember their dreams can often recall one or two unusual dreams from their lives — dreams with so much intensity and vividness they cannot be forgotten. Dream recall tends to respond to waking interest. The more people pay attention to their dreams, the more dreams they are likely to remember.

8. Dreaming helps the mind to process information from waking life, especially experiences with a strong emotional charge.

From a cognitive psychological perspective, dreaming functions to help the mind adapt to the external environment by evaluating perceptions, regulating emotional arousal, and rehearsing behavioral responses. Dreaming is like a psychological thermostat, preset to keep us healthy, balanced, and ready to react to both threats and opportunities in the waking world. Post-traumatic nightmares show what happens when an experience is too intense and painful to process in a normal way, knocking the whole system out of balance.

9. The mind is capable of metacognition in dreaming, including lucid self-awareness.

During sleep and dreaming, the mind engages in many of the activities most associated with waking consciousness: reasoning, comparing, remembering, deciding, and monitoring one’s own thoughts and feelings. Lucid dreaming is one clear example of this, and so are dreams of watching oneself from an outside perspective. These kinds of metacognitive (thinking about thinking) functions were once thought to be impossible in dreaming, but current research has proven otherwise. Dreaming has available the full range of the mind’s metacognitive powers, although in different combinations from those typically active in ordinary waking consciousness.

For further reading

Barrett, Deirdre and Patrick McNamara, ed.s. The New Science of Dreaming. Westport: ABC-Clio, 2007.

Bulkeley, Kelly. Big Dreams: The Science of Dreaming and the Origins of Religion. New York: Oxford University Press, 2016.

Domhoff, G. William. Finding Meaning in Dreams: A Quantitative Approach. New York: Plenum, 1996.

Hurd, Ryan and Kelly Bulkeley, ed.s. Lucid Dreaming: New Perspectives on Consciousness in Sleep. Westport: ABC-Clio, 2014.

Kryger, Meir H., Thomas Roth, and William C. Dement, ed.s. Principles and Practice of Sleep Medicine. Fourth Edition. Philadelphia: Elsevier Saunders, 2005.

Maquet, Pierre, Carlyle Smith, and Robert Stickgold, ed.s. Sleep and Brain Plasticity. New York: Oxford University Press, 2003.

Pace-Schott, Edward, Mark Solms, Mark Blagrove, and Stevan Harnad, ed.s. Sleep and Dreaming: Scientific Advances and Reconsiderations. Cambridge University Press, 2003.

Pagel, James. The Limits of Dream: A Scientific Exploration of the Mind/Brain Interface. New York: Academic Press, 2010.

Solms, Mark. The Neuropsychology of Dreams: A Clinico-Anatomical Study. Mahway: Lawrence Erlbaum, 1997.

Chronobiology: The Science of Time

Most of us have very little knowledge about the human body’s inner clock. However, a young science from Europe called Chronobiology has been gaining importance over the past 30 years. Chronobiology refers to the day-night cycle that affects the human organism when the earth rotates. Since the beginning of mankind, human history has been shaped by light and darkness. Genetically manifested timers reside deep in our bodies that control this fundamental rhythm. The more intelligently we absorb their information, the more useful it is. This connection is important in the prevention and treatment of diseases, as well as for the healing process.

The beginnings of Chronobiology date back to the 18th century. The astronomer Jean Jacques d’Ortous de Mairan reported daily leaf movements of the mimosa. Through experimentation he was able to show that the leaves continue to swing in a circadian rhythm, even in permanent darkness. Renowned scientists like Georg Christoph Lichtenberg, Christoph Wilhelm Hufeland, Carl von Linné, and—most importantly—Charles Darwin reported similar rhythmic phenomena. Yet it wasn’t until the 20th century when chronobiology research truly began. Wilhelm Pfeffer, Erwin Bünning, Karl von Frisch, Jürgen Aschoff, Colin Pittendrigh and Arthur Winfree are among its pioneers.

The Three Basic Cycles of Chronobiology

Infradian Rhythms

(derived from the Latin word infra, meaning “below,” and the Latin word diem, meaning “day” – breaking down the origin of the word, Infradian means the period of this rhythm is longer than 24-hours, therefor, the frequency is below/under those of one day.)

These are rhythms that last more than 24 hours. These are repeated only every few days, weeks, months, or even once per year.

Good examples are seasonal rhythms such as bird migration, lunar rhythms (which follow the phases of the moon, or about 29.5 days) and semi-lunar rhythms (about 14 days) that are associated with tidal cycles. Another example is unpredictable rhythms (aka “non-circadian rhythms” that do not have any environmental correspondence) such as a woman’s menstrual cycle.

Ultradian Rhythms

(derived from the Latin ultra, meaning “beyond,” and from the Latin word diem, meaning “day” – breaking down the origin of the word, Ultradian means the period of this rhythm is shorter than 24-hours, and therefor has a frequency beyond/higher than one day.)

These are biological rhythms that are shorter than 24-hours. There are many physiological functions of the human body that exemplify an ultradian rhythm. These rhythms have multiple cycles in one day. An adult, for example, has an exertion and rest cycle about every two hours.

Ultradian rhythms regulate physical, emotional and spiritual functions. They often last several hours and include the ingestion of food, circulation of blood, excretion of hormones, different stages of sleep and the human performance curve. These processes are built into our bodies in millions of ways. Some last merely seconds, such as the control of breathing. Some last only milliseconds, such as the majority of processes that take place in the cell on a microcirculatory level. Tidal rhythms (about 12.4 hours) are often observed in marine life, follow the transition of the tides from high to low and back and have a special function for many people living inside a surf zone.

Circadian Rhythms

(from Latin “circa” meaning “around,” and “diem” meaning “day”)

These are rhythms that take approximately 24-hours, i.e. the human sleep/wake cycle or the leaf movements of plants. Many effects of circadian rhythms directly and immediately affect humans, therefore, they are the most extensively researched. Thus, all further explanations refer to circadian rhythms.

Chronobiology Today

The field of chronobiology is rapidly expanding around the world. Medical professionals, researchers and the general population are beginning to see the benefits of using chronobiological principles in everything from medication administration to determining the most effective time of day to exercise. Chronobiology is being used in the study of genetics, endocrinology, ecology, sports medicine and psychology, to name a few.

The chronopharmacology branch of chronobiology has been especially lucrative. Thousands of studies have yielded information on how the precise timing of a medication or supplement can decrease side effects, have a more potent effect on the target organ system or disease and even completely disrupt a physiological process.

Many renowned institutions have added departments, labs and curriculum centered on the study of chronobiology. These institutions have provided groundbreaking research and insights that have helped shape modern medicine and the understanding of our innate biological rhythms. Melatonin, also referred to as the “mother hormone of chronobiology,” the effects of light on a variety of diseases and the phenomenon of chronotypes have been areas of particular interest.

While chronobiology is still considered a young science, the possibilities it presents are endless. Our methods of research are becoming more advanced and with that brings the reality that chronobiology will eventually become the leading scientific discipline.


Sleep is as essential to our daily needs as food and water. Although we may feel that sleep simply rests our tired bodies, our brain remains active throughout the night. Sleep plays a critical role in brain as well as physical functioning.

What Happens When We Sleep?

Our internal body clock, called a circadian clock, tells us when we are ready to sleep. There are actually several circadian clocks in the body, found in the brain and other organs. They are triggered by cues such as daylight (we feel alert) and darkness (we feel drowsy). These clocks can also be triggered by artificial bright light or stimulants like caffeine and alcohol that cause us to feel awake even if it is nighttime.

There are several phases of sleep our body experiences. They are classified as REM (rapid eye movement) and non-REM sleep. We cycle repeatedly through these phases about 4-6 times throughout the night, and it is not uncommon to wake up briefly between cycles.

Non-REM sleep

Stage 1. You transition from being awake to a restful state.

Stage 2. You are in a light sleep state. Your breathing, heart rate, and muscle movements slow down. Brain activity also slows, and your body temperature drops.

Stage 3. You are in a deep sleep state. This stage often occurs early in the sleep cycle immediately following light sleep. Your heart rate and breathing are the slowest during this phase, and you are not easily awakened. Events of the day are processed and stored in your memory. A lack of deep sleep can leave one feeling tired in the morning even if achieving an adequate duration of sleep.

During REM, your pupils twitch and move quickly from side to side underneath closed eyelids. Brain activity rises as you breathe faster and your heart rate increases. It is the phase of sleep when dreams are most common, and certain nerves signal your limbs to become temporarily paralyzed so you do not act out the dream. REM tends to occur later at night and into early morning. Memory is processed and stored during REM sleep.

Why do we dream?

Hormones that Regulate Sleep Cycles

There are various neurotransmitters and hormones released by the brain that send signals to promote sleep or wakefulness. [1] Many of these chemicals are stimulated by light or darkness.

  • GABA is a neurotransmitter that decreases nerve cell activity, playing a major role in allowing the body to sleep.
  • Adenosine is another neurotransmitter that gradually accumulates in the brain during the day, and at high concentrations makes us sleepy at night. Caffeine in coffee and other beverages can keep us awake as it blocks brain receptors for adenosine.
  • Melatonin is a hormone released by the brain when it is dark. It travels to cells to tell the body to sleep. Sunlight or exposure to light inhibits the production of melatonin and increases the release of cortisol, which awakens us. If we are exposed to too much artificial light (such as the blue light emitted from smartphones or televisions) late at night, less melatonin may be released making it harder to fall asleep.
  • Serotonin, the body’s “feel-good” chemical, is a neurotransmitter associated with both sleep and being awake. The brain releases this chemical during daylight but also uses it to form melatonin at night.
  • Hormones that counteract sleep include norepinephrine, adrenaline, histamine, and cortisol. These are secreted in response to stress and cause the body to be awake and alert. If one experiences prolonged or chronic stress, the body releases adrenocorticotropic hormone (ACTH), which in turn releases cortisol. Levels of ACTH tend to be higher in people who have insomnia.

Immediate Effects of Sleep Deprivation

About one-third of American adults do not get enough sleep each night, according to the Centers for Disease Control and Prevention. [2,3] Short sleep duration in adults is defined as less than 7 hours of sleep in 24 hours. About 40% of adults report unintentionally falling asleep during the day at least once a month, and up to 70 million Americans have chronic sleep problems. Because of the public health burden of poor sleep health, achieving sufficient sleep in children and adults was included as a goal in the Healthy People 2020 goals. [4]

Sleep helps to process your thoughts from the day as well as store memories, so a lack of good-quality sleep can lead to difficulty focusing and thinking clearly. You may feel tired, irritable, or anxious during the day. Performance at work or school may suffer. Your reaction time may be slowed, increasing the risk of driving accidents.

In children, insufficient sleep can lead to attention and behavior problems or hyperactivity. In the elderly, lack of sleep may decrease focus and attention, leading to a greater risk of falls, bone fractures, and car accidents.

There are several reasons people may get insufficient sleep:

  • Poor sleep habits (watching television or using screens late at night, drinking caffeinated or alcoholic beverages at night, not following a regular sleep schedule).
  • Your sleep environment is too noisy, too light or otherwise not conducive to sleep.
  • You attempt to sleep outside of the body’s natural circadian clock (working an overnight shift and trying to make up for sleep during the day).
  • You have a sleep disorder, such as sleep apnea, insomnia, or periodic limb movements that reduces deep or REM sleep or causes frequent awakenings.
  • You have a medical condition such as heart, lung or kidney disease, or chronic pain, which causes frequent awakenings.

Sleep Deficiency and Disease Risk

If you experience continued sleep deprivation, you will develop a condition called sleep deficiency. This is a state in which you cannot make up the many lost hours of sleep. Sleep deficiency increases the risk of obesity, diabetes, cardiovascular disease, depression, and even early death.

Several studies show that sleep deprivation (i.e., regularly less than 7 hours of sleep a night) is a risk factor for obesity. A Nurses’ Health Study found an association between those who slept the least (5 hours or less a night) and having the highest BMI and greatest weight gain. [5] One reason may be a disruption in appetite hormones that regulate feelings of hunger (called ghrelin) versus satisfaction (called leptin). Ghrelin levels rise while leptin levels drop with lack of sleep this can cause higher calories to be consumed due to experiencing strong hunger at the same time that one feels less satiated after eating. A preference for foods high in fat and carbohydrate has been observed. [6,7] The risk of hunger also increases simply by being awake longer, which prolongs the time from the last meal eaten to bedtime. [6] Insufficient sleep also can trigger the “reward” areas in your brain to crave high fat, high caloric foods. [8]

One may think that getting less sleep would mean more activity due to being awake longer and therefore using more calories. However, studies have found either no increase or very small increases in energy expenditure with sleep deprivation, and even a tendency towards reduced physical activity due to fatigue. [9] Less physical activity combined with the increased calorie intake associated with sleep deprivation increases the risk of obesity.

Other effects of poor sleep include increased fat storage in the belly area, higher body mass index, poorer quality diet, and decreased insulin sensitivity. [6,10] Interestingly, some studies have also shown that longer sleep times (more than 9 hours) are also associated with developing belly fat compared with sleeping 7-8 hours a night. [7]

Epidemiological and laboratory studies show a higher risk of diabetes mellitus with both too little sleep (less than 7 hours) and longer sleep durations (more than 9 hours). Metabolic changes may occur with chronic insufficient sleep, such as higher cortisol levels leading to increased blood glucose. Clinical studies have found both increased glucose and insulin levels (suggesting insulin resistance) and reduced insulin sensitivity in sleep-deprived individuals. [11] Disruption in the regulation of appetite hormones as seen with higher ghrelin and lower leptin levels may lead to increased food intake and weight gain, also increasing the risk of insulin resistance. [11]

Some people who have insufficient sleep have a condition called obstructive sleep apnea, which blocks breathing in the upper airway tubes, often because of increased fat in the tongue. Sleep apnea is independently associated with insulin resistance a lack of oxygen while sleeping can cause oxidative stress and inflammation that are believed to progress toward insulin resistance. [11]

Both shorter and longer sleep durations are associated with cardiovascular diseases. [12,13] Proposed reasons include activation of the sympathetic nervous system and impaired endothelial function, which can lead to elevated blood pressure and hardening of arteries. There may also be greater release of pro-inflammatory cells and decreased immune function. Metabolic changes include a disruption in appetite hormones and circadian rhythms that lead to inflammatory conditions. [14]

  • People sleeping less than 6 hours a night, particularly women, were 20-32% more likely to develop hypertension compared with those sleeping 7-8 hours a night. [12] Having 5 or less hours of sleep a night was associated with double the risk of developing hypertension in another study. [15]
  • In a Nurses’ Health Study, the risk of heart disease was almost 1.4 times higher in women sleeping 5 hours or less a night and 9 hours or more a night compared with those sleeping 8 hours a night. [16]
  • In postmenopausal women, those who slept 5 hours or less or 10 hours or more a night had a 25% and 45% increased risk of heart disease, respectively. [17]
  • Individuals with inadequate sleep as well as long sleep durations showed an increased risk of strokes. [12]
  • Individuals with poor sleep quality or insomnia symptoms are 40% more likely to develop hypertension [18]
  • People with obstructive sleep apnea are at increased risk for stroke, heart attack, and heart failure.

Poor sleep and insomnia (an inability to sleep or stay asleep) are associated with depression, especially if the insomnia becomes chronic. [19] Insomnia is also associated with increased likelihood of insomnia relapsing over time. Poor sleep quality can impair functioning, increase fatigue, and lead to mood changes. The reverse is also true in which depressive symptoms of intense sadness or hopelessness can interrupt sleep. Insomnia as well as oversleeping are common signs of clinical depression, according to the National Institute of Mental Health. [20] Treating the depression may lead to improvements in sleep quality. If there is an underlying medical disorder causing the insomnia such as obstructive sleep apnea or chronic pain, then treatment should address these first.

Prospective cohort studies have found that both a chronic lack of sleep (less than 7 hours) and long sleep durations (more than 8 hours) are associated with greater risk of death from all causes. [7,13] Obstructive sleep apnea and insomnia are also associated with increased mortality. [21,22] However, long sleep durations appear to be more associated with increased risk of mortality than inadequate sleep. [13] Some studies show that women may have greater risk of mortality related to short sleep durations than men. [23] Longer sleep times are associated with several factors that are associated with mortality, including fatigue, stress, obstructive sleep apnea, and increased inflammation of heart arteries. More research with randomized controlled trials is needed to better understand the reasons for these findings.

Medical Conditions that Interfere with Sleep

  • Obstructive sleep apnea (OSA)—Symptoms of OSA include snoring or gasping for air that causes interruptions in sleep and prevention of good-quality sleep. Sleep apnea also causes oxygen levels to drop during sleep, which can pose a stress on the heart, brain and other organs. People with OSA may not be aware that they are awakening frequently in the night, but do not get refreshed sleep, feeling excessively sleepy or tired during the day. Continuous positive airway pressure (CPAP) devices may be prescribed, which provides pressurized air to the nose and throat, preventing the upper airway from collapsing. Another common treatment is dental devices that move the jaw forward and increasing the airway size. Obesity is a risk factor for OSA because carrying extra weight, particularly in the neck area, can contribute to obstructed breathing passages. About 70% of adults with OSA have obesity, and a significant improvement in OSA is seen with weight reduction. [7] OSA is a risk factor for insulin resistance, hypertension, type 2 diabetes, cardiovascular disease, and early mortality. [7]
  • Restless leg syndrome—This condition is associated with discomfort in the legs accompanied by an urge to move, which disrupts sleep. It is believed that abnormal levels of the neurotransmitter dopamine may be responsible, so medications are given to correct this. In some cases, low levels of iron can result in this disorder.
  • Insomnia—This condition is defined as the inability to sleep or stay asleep. An individual may have a hard time falling asleep, or may sleep but then awaken in the early morning and be unable to return to sleep. Short-term insomnia can be caused by stress or traumatic events (divorce, job loss, death of a loved one). Chronic or long-term insomnia may be caused by ongoing anxiety, working different work shifts that disrupt the body’s circadian rhythms, poor sleep habits, medical conditions that can interrupt sleep (chronic pain, gastroesophageal reflux disease), or medications that have a stimulating effect. Insomnia often can be treated with behavioral therapies, although sometimes sleep medications are prescribed.
  • Genetic—Studies have found specific gene variants that are associated with insomnia. [24,25] The same genes for insomnia were also associated with higher levels of body fat, depression, and heart disease. Research has also found that sleep apnea clusters within families, and genes have been identified that appear to increase risk for sleep apnea as well as cardiovascular disease. [26] More research is needed in this area.

What if I work the night shift?

  • Request to work the same shift several nights in a row, to avoid flipping between day and night shift schedules on consecutive days. This helps to regulate the circadian system.
  • Commit to a consistent sleep schedule, darkening the bedroom with blackout shades, and creating a quiet atmosphere as much as possible. You might reduce light exposure even earlier by wearing sunglasses as soon as you leave work. To reduce noise, wear earplugs and use a white noise machine to block sounds.
  • After finishing a night shift, try to return home and go to bed as soon as possible. Running errands, watching television, talking with family, or exercising can re-energize your body so that falling asleep becomes more difficult.
  • Although it is tempting to run errands and attend medical appointments during the day when places are less crowded, try to minimize doing them immediately after work so that you can return home and honor your sleep schedule.
  • Try to keep a set meal schedule. Do meal planning to ensure that quick easy meals are ready when you arrive home, and bring prepped meals/snacks to work for overnight shifts to prevent reliance on fast food and takeout meals. Try to avoid eating a large meal right before bed, which can increase the risk of reflux and indigestion.

Sleep Deficiency and Eating Behaviors

Epidemiological studies show that insufficient sleep is independently associated with a higher risk of obesity. Clinical studies of of sleep-restricted adults show an increased hunger and calorie intake when participants are allowed free access to food. [7] A preference for late evening or nighttime food intake and increased snacking has been observed. [9] There also appears to be a food preference for higher carbohydrate and fat foods, which could partly explain the overall higher calorie intake.

Changes in hormone levels that signal either hunger or satiety have also been observed in clinical sleep restriction studies. Leptin is a hormone associated with satisfaction. When food enters the stomach, leptin is released from fat cells and travels to the brain where it signals the body to stop eating by creating a sensation of fullness. People with obesity may actually have very high levels of leptin the more body fat one has, the more leptin is produced in fat cells. However, a condition called leptin resistance may occur in which the brain does not receive the usual signal from leptin to stop eating. In response, more and more leptin is released. Lower leptin levels as well as high leptin levels suggesting leptin resistance have been observed in sleep-deprived adults. [7]

Ghrelin, the “hunger hormone,” typically has the opposing action of leptin. It is released in the gut and sends hunger signals to the brain when someone is not eating enough. About three hours after eating a meal, ghrelin levels drop. Clinical studies have found that sleep restriction leads to elevated ghrelin levels. [9]

Despite this interesting theory of poor sleep leading to changes in appetite hormone levels, other studies have found no changes and therefore the association is still inconclusive. [9] Conflicting findings may be due to differences in the study participants (e.g., age, gender) and differences in how the researchers defined the duration and severity of sleep restriction.

How Much Sleep Do We Need?

Sleep needs change as we age, with the average person generally requiring less sleep at older ages. However, specific sleep amounts vary by individual. According to the National Sleep Foundation and American Academy of Sleep Medicine (AASM), newborns need the most sleep, at 14-17 hours a day, followed by infants at 12-16 hours a day including naps. Toddlers need about 10-14 hours a day. Preteens and teenagers need about 8-12 hours a night, and adults about 7-8 hours a day. [29] A consensus by the AASM and Sleep Research Society recommends that adults should sleep 7 or more hours a night to promote optimal health. [30]

Despite these general recommendations on sleep duration, individual differences in sleep requirements exist. In most epidemiologic studies, increased risk of adverse health outcomes such as obesity, diabetes, and cardiovascular disease, has been observed among those who reported sleeping 5 hours or less per day, and 9 hours or more per day. Thus, a range of sleep hours (more than 5 and less than 9) is considered appropriate for most healthy adults.

Other factors such as quality of sleep are important, because just meeting the total recommended sleep hours may not be enough if one wakes up frequently in the night. A common belief is that lost sleep from a late night out or studying can be recovered by “sleeping in” another day or taking naps. However, both of these methods disrupt the body’s circadian rhythms and may deprive the body of deeper sleep stages. In fact, increased variability in how much sleep we get from night to night is associated with an increased risk of developing metabolic and heart diseases. [31] It is important to respond, whenever possible, to the body’s natural signals of sleepiness.

What about supplements, medicines, and other therapies for sleep?

Herbal supplements

Two popular herbal supplements, melatonin and valerian, are used as sleep aids. Melatonin has been shown to quicken time to sleep and have modest benefits on sleep duration and quality, but can cause daytime drowsiness. It is well tolerated in adults with few reported adverse events in doses up to 10 mg. The American Academy of Sleep Medicine (AASM) recommends the judicious use of melatonin for certain sleep and circadian disorders such as shift work disorder or jet lag. [32]

Valerian contains small amounts of GABA, a sleep-promoting neurotransmitter, and some studies have shown that valerian can improve sleep. However, other studies have found no difference in sleep when taking valerian compared with placebo, and there appears to be minimal benefit in those who have diagnosed insomnia. The AASM does not recommend valerian for insomnia disorder. [32]

It is important to note that supplements are not regulated by the Food and Drug Administration. Therefore doses and preparations of these herbs can vary widely. A study of 31 melatonin products found that the melatonin levels in the pills ranged between 83%-478% of the dose reported on the label. [32] More than 70% of the products varied from the labeled dose by more than 10%. If supplements are used, look for a label verifying its quality from a third-party, such as from the U.S. Pharmacopeia.

Sleep medicines

Common medicines prescribed for sleep include sedatives such as benzodiazepines (e.g., Valium, Xanax, Klonopin, Ativan*). They help with falling asleep initially, but tend to reduce the amount of deeper sleep. They are not recommended for long-term use because they can worsen insomnia, increase depression, and impair memory, and are associated with increased risk of falls, cancer, and early death. [33] Long-term use of benzodiazepines can promote psychological dependence, and there is a risk of addiction and abuse. [34] Tolerance can also develop over time, requiring larger doses to maintain their effectiveness. Because of these side effects, benzodiazepines are not recommended to treat insomnia in older adults. [34] There are other classes of sleep medications including non-benzodiazepines (e.g., Lunesta, Ambien) and antidepressants (e.g., Zoloft) that also quicken the time to fall asleep but may interfere with deeper sleep stages. Anticholinergic medications (e.g., Benadryl) can increase the risk for cognitive impairment and decline. Generally, sleep medicines are most effective when used occasionally or for a short time of less than one month. The American Academy of Sleep Medicine (AASM) recommends that cognitive behavioral therapy be used as the initial treatment for insomnia. [*The inclusion of brand names is included for reference and does not constitute an endorsement. The Nutrition Source does not endorse any specific brands.]

Other therapies

Randomized clinical trials have shown that cognitive behavioral therapies (CBT) for sleep such as minimizing napping during the day, relaxation training, breathing exercises, and sleep hygiene are highly effective and recommended as first-line treatments for insomnia. [34,32] They have been found more effective than medications for the long-term management of insomnia. People may be asked to keep a sleep journal to record sleep habits and activities performed around bedtime, which can help determine the most appropriate CBT.

Sleep Hygiene Tips

  • Set a sleep schedule and stick to it. Try to go to bed at night and awaken in the morning around the same times, even on weekends. This helps to regulate the body’s sleep cycles and circadian rhythms.
  • Try to exercise at some point in the day but avoid vigorous activity (running, fast dancing, high-intensity interval training or HIIT) one hour before bedtime. Regular exercise of adequate intensity can promote muscle relaxation and deeper sleep later on.
  • Try to avoid large meals, heavy snacking, or alcohol 2-3 hours before bed.
  • If you are sensitive to caffeine, try to avoid drinking caffeinated beverages 4-6 hours before bedtime.
  • Stop using electronic devices an hour before bed, especially those emitting blue light such as smartphones, tablets, and televisions.
  • Schedule before-bed activities to signal that you are winding down, such as changing into pajamas and brushing teeth.
  • Create a quiet, dark, relaxing environment in your bedroom. Dim the lights and turn off your cell phone’s sound and vibration modes if possible.
  • Ensure a comfortable temperature, as feeling too hot or cold can disrupt sleep.
  • Create calming bedtime rituals such as practicing deep breathing exercises, doing light yoga stretches, or listening to soothing relaxing music. Many meditation podcasts, apps, and YouTube videos offer these tools for free.
  • If you awaken and can’t return to sleep, don’t stay in bed. Get up and do quiet relaxing activities, such as reading, until you feel tired enough to fall back asleep.

Does exercising at night disrupt sleep?

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Future directions

The development of behavioral assays to measure sleep in fruit flies, C. elegans and zebrafish has led to the rapid discovery of genetic and neural processes regulating sleep. These findings pave the way for investigating the function of sleep, and how it is altered by an animal's ecological environment and evolutionary history. In recent years, progress using behavioral criteria to define sleep in a number of novel model organisms including the jellyfish, Aplysia and cavefish have potential to provide new insight into the biological and functional basis of sleep regulation. Many animals are uniquely suited for studying specific functions of sleep, including the use of Aplysia to study the relationship between sleep and memory formation, and the honeybee to examine interactions between sleep and social experience. We propose that by characterizing sleep in additional animal models of evolution ranging from organisms with simplified nervous systems such as the starlet sea anemone Nematostella to the three-spined stickleback, a model of microevolution, we will gain a better understanding of how ecology and life history traits regulate sleep. The emergence of sleep studies in organisms with simplified nervous systems or defined evolutionary history, combined with the development of gene-editing technology, provide novel avenues to investigate the evolution of function of sleep. Together, these integrative approaches in diverse models will help define the relevance of genetic and neural principles regulating sleep to the broader animal kingdom.

Watch the video: Was passiert, wenn wir schlafen? Schlafzyklen, Schlafphasen uvm. #3 Level Up Your Sleep! (December 2021).