What happens to the brain during sleep versus unconsciousness?

How does being unconsciousness differ from being asleep and whether it causes breaks in consciousness?

What Happens in Your Body and Brain While You Sleep

You might think of sleep as the negative time in your day when nothing on your to-do list gets done. Your brain and several other systems in your body see it quite differently.

“Your brain is actually very active during sleep doing important things — it’s not just resting,” says Carl W. Bazil, MD, PhD, the Caitlin Tynan Doyle Profesor of Neurology at Columbia University Medical Center. “And if you don’t get sleep you don’t function on a number of levels the way you should.”

(Everything from learning to your mood to your risk of getting sick and becoming obese can get thrown off kilter.)


Sleep Rx A Guide to BETTER Sleep

Physiologically sleep is defined as a state our bodies enter into during which brain wave activity changes and our nervous system is less reactive to external stimuli (i.e. we temporarily leave consciousness). But our sleep is not constant throughout the night. We actually cycle through four distinct sleep phases multiple times (five if you count “awake” as one stage), Bazil, who is also Director of the Division of Epilespy and Sleep at Columbia University College of Physicians and Surgeons, tells NBC News BETTER.

There are two stages of light sleep. The lightest is the stage of sleep you’re likely in if you nod off during a lecture when consciousness is decreased, but the brain is still processing some information around you (sometimes hearing your name or another stimulus will jolt you awake). Intermediate light sleep is slightly deeper, which is harder to awaken from, Bazil explains.

Your brain is actually very active during sleep doing important things — it’s not just resting.

Deep slow-wave sleep is the next stage of sleep. This is the deepest, most restful, and most restorative stage of sleep, when it’s hardest to awaken. If you do get woken up during this stage of sleep you’re likely to feel groggy. And finally, there’s REM sleep (short for “rapid eye movement sleep”), which is when we dream. Our bodies tend to spend more time in restful slow wave sleep earlier in the night when our bodies and minds are most tired. Later in the night we tend to spend more time in REM sleep.

Brain may flush out toxins during sleep

NIH-funded study suggests sleep clears brain of damaging molecules associated with neurodegeneration.

Scientists watched dye flow through the brain of a sleeping mouse. Nedergaard Lab, University of Rochester Medical Center.

A good night’s rest may literally clear the mind. Using mice, researchers showed for the first time that the space between brain cells may increase during sleep, allowing the brain to flush out toxins that build up during waking hours. These results suggest a new role for sleep in health and disease. The study was funded by the National Institute of Neurological Disorders and Stroke (NINDS), part of the NIH.

“Sleep changes the cellular structure of the brain. It appears to be a completely different state,” said Maiken Nedergaard, M.D., D.M.Sc., co-director of the Center for Translational Neuromedicine at the University of Rochester Medical Center in New York, and a leader of the study.

For centuries, scientists and philosophers have wondered why people sleep and how it affects the brain. Only recently have scientists shown that sleep is important for storing memories. In this study, Dr. Nedergaard and her colleagues unexpectedly found that sleep may be also be the period when the brain cleanses itself of toxic molecules.

Their results, published in Science, show that during sleep a plumbing system called the glymphatic system may open, letting fluid flow rapidly through the brain. Dr. Nedergaard’s lab recently discovered the glymphatic system helps control the flow of cerebrospinal fluid (CSF), a clear liquid surrounding the brain and spinal cord.

“It’s as if Dr. Nedergaard and her colleagues have uncovered a network of hidden caves and these exciting results highlight the potential importance of the network in normal brain function,” said Roderick Corriveau, Ph.D., a program director at NINDS.

Initially the researchers studied the system by injecting dye into the CSF of mice and watching it flow through their brains while simultaneously monitoring electrical brain activity. The dye flowed rapidly when the mice were unconscious, either asleep or anesthetized. In contrast, the dye barely flowed when the same mice were awake.

“We were surprised by how little flow there was into the brain when the mice were awake,” said Dr. Nedergaard. “It suggested that the space between brain cells changed greatly between conscious and unconscious states.”

To test this idea, the researchers inserted electrodes into the brain to directly measure the space between brain cells. They found that the space inside the brains increased by 60 percent when the mice were asleep or anesthetized.

“These are some dramatic changes in extracellular space,” said Charles Nicholson, Ph.D., a professor at New York University’s Langone Medical Center and an expert in measuring the dynamics of brain fluid flow and how it influences nerve cell communication.

Certain brain cells, called glia, control flow through the glymphatic system by shrinking or swelling. Noradrenaline is an arousing hormone that is also known to control cell volume. Similar to using anesthesia, treating awake mice with drugs that block noradrenaline induced unconsciousness and increased brain fluid flow and the space between cells, further supporting the link between the glymphatic system and consciousness.

Previous studies suggest that toxic molecules involved in neurodegenerative disorders accumulate in the space between brain cells. In this study, the researchers tested whether the glymphatic system controls this by injecting mice with labeled beta-amyloid, a protein associated with Alzheimer’s disease, and measuring how long it lasted in their brains when they were asleep or awake. Beta-amyloid disappeared faster in mice brains when the mice were asleep, suggesting sleep normally clears toxic molecules from the brain.

“These results may have broad implications for multiple neurological disorders,” said Jim Koenig, Ph.D., a program director at NINDS. “This means the cells regulating the glymphatic system may be new targets for treating a range of disorders.”

The results may also highlight the importance of sleep.

“We need sleep. It cleans up the brain,” said Dr. Nedergaard.

This work was supported by grants from the NINDS (NS078167, NS07830, NS028642).

For more information about neurological disorders and the latest neuroscience research:

NINDS is the nation’s leading funder of research on the brain and nervous system. The NINDS mission is to reduce the burden of neurological disease – a burden borne by every age group, by every segment of society, by people all over the world.

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit

NIH&hellipTurning Discovery Into Health ®


Xie et al “Sleep initiated fluid flux drives metabolite clearance from the adult brain.” Science, October 18, 2013. DOI: 10.1126/science.1241224

Understanding the anesthetized brain

Since 1846, when a Boston dentist named William Morton gave the first public demonstration of general anesthesia using ether, scientists and doctors have tried to figure out what happens to the brain during general anesthesia.

Though much has been learned since then, many aspects of general anesthesia remain a mystery. How do anesthetic drugs interfere with neurons and brain chemicals to produce the profound loss of consciousness and lack of pain typical of general anesthesia? And, how does general anesthesia differ from sleep or coma?

Emery Brown, an MIT neuroscientist and practicing anesthesiologist at Massachusetts General Hospital, wants to answer those questions by bringing the rigorous approach of neuroscience to the study of general anesthesia. In a review article published online Dec. 29 in the New England Journal of Medicine, he and two colleagues lay out a new framework for studying general anesthesia by relating it to what is already known about sleep and coma.

Such an approach could help researchers discover new ways to induce general anesthesia, and improve our understanding of other brain states such as drug addiction, epilepsy and Parkinson’s disease, says Brown, who is a professor in the Department of Brain and Cognitive Sciences and the Harvard-MIT Division of Health Sciences and Technology.

“Anesthesia hasn’t been attacked as seriously as other questions in neuroscience, such as how the visual system works,” says Brown, who started studying general anesthesia several years ago. Neuroscientists study vision at all levels, including molecular, neurophysiological and theoretical. “Why shouldn’t we be doing the same thing for questions of general anesthesia?” he asks.

Anesthesia, sleep and coma

In the United States, 60,000 surgical patients undergo general anesthesia every day. Though doctors sometimes tell their patients that they will be “going to sleep” during a surgical procedure, that is not accurate, says Brown. “This may sound nitpicky, but we need to speak precisely about what this state is,” he says. “This paper is an attempt to start at square one and get clear definitions in place.”

General anesthesia is not simply a deep sleep, Brown emphasizes. In fact, part of the reason that he and his colleagues wrote the NEJM paper is to make doctors more aware of the differences and similarities between general anesthesia, sleep and coma. Co-author Ralph Lydic, a neuroscientist at the University of Michigan, is an expert in sleep, and Nicholas Schiff, another co-author and neurologist at Weill Cornell Medical College, is an expert in coma.

In the NEJM paper, the authors define general anesthesia as a “drug-induced, reversible condition that includes specific behavioral and physiological traits” — unconsciousness, amnesia, pain numbing, and inability to move. Also key is the stability of body functions such as respiration, circulation and temperature regulation.

Using EEG (electroencephalography) readings, which reveal electrical activity in the brain, Brown and his colleagues show that even the deepest sleep is not as deep as the lightest general anesthesia.

Throughout the night, the sleeping brain cycles through three stages of non-REM (rapid eye movement) sleep, alternating with REM sleep, which is when most dreaming occurs. Each of these has a distinctive EEG pattern. None of those resembles the EEG of a brain under general anesthesia, however. In fact, general anesthesia EEG patterns are most similar to those of a comatose brain. As Brown points out, general anesthesia is essentially a “reversible coma.”

Indeed, the early clinical signs of emergence from general anesthesia — return of regular breathing, return of movements and cognition — parallel those of recovery from a coma, though compressed over minutes instead of the hours (or even years) it takes to come out of a coma.

In addition, the paper offers explanations for the clinical signs of loss of consciousness induced by general anesthesia, based on the underlying neural circuits. The authors also explain a phenomenon known as “paradoxical excitation,” in which anesthetic drugs actually increase brain activity while inducing loss of consciousness. As one example, the authors describe how the drug ketamine produces unconsciousness by inhibiting neurons whose job is to restrain other neurons, leading to overexcitation in several brain regions. This overexcitation explains the hallucinations seen with ketamine, a common drug of abuse also known as “Special K.”

Toward better anesthetics

Though general anesthesia is seen as a routine procedure, it does hold some risk. Estimated mortality directly attributable to anesthesia is one in 250,000. The drug believed to have caused Michael Jackson’s death, propofol, is a potent anesthetic.

“Anesthetics are very powerful medications with a very narrow safety margin, as evidenced by the unfortunate events surrounding Michael Jackson’s death,” says Andreas Loepke, associate professor of clinical anesthesia and pediatrics at the University of Cincinnati College of Medicine. “These medications carry potent side effects, such as respiratory depression, loss of protective airway reflexes, blood-pressure instability, as well as nausea and vomiting.”

A better understanding of how general anesthesia works at the cellular and molecular level could help researchers develop anesthestic drugs that lack those side effects, says Loepke, who was not involved with this paper.

Brown also hopes his work will lead to new anesthetic drugs. To that end, he has several ongoing studies in which he is recording electrical activity from the brains of animals under general anesthesia, as well as imaging human brains. From these studies, he hopes to learn more about which parts of the brain become more or less active during general anesthesia.


In contrast to unconsciousness induced by most hypnotic agents, which is predominantly associated with slow EEG patterns, unconsciousness induced by the NMDA antagonist ketamine is associated with active EEG patterns. 86,87 Seizures are commonly associated with active, highly organized EEG patterns. Unconsciousness due to seizures most likely results from organized, aberrant brain activity that impedes the normal communications necessary to maintain arousal and cognition. 88 Similarly, a highly active brain state most likely plays a role in unconsciousness induced by ketamine. Ketamine preferentially inhibits NMDA-mediated glutamatergic inputs to GABAergic interneurons, leading to aberrant excitatory activity in the cortex, hippocampus, and limbic system and ultimately unconsciousness ( Fig. 4 ). 89,90 Hallucinations may result because the aberrant activation allows the association of information in a manner that is inconsistent in time and space. The hallucinations can be mitigated by the concurrent administration of a benzodiazepine, 91 which presumably acts to enhance GABAA-mediated activity of the interneurons and hence leads to sedation. The potent antinociceptive effects of ketamine on NMDA receptors in the spinal cord and its inhibition of acetylcholine release from the pons also contribute to unconsciousness ( Fig. 4 ). 92�

Ketamine binds preferentially to N-methyl-D-aspartate (NMDA) receptors on inhibitory interneurons in the cortex, limbic system (amygdala), and hippocampus, promoting an uncoordinated increase in neural activity, an active electroencephalographic pattern, and unconsciousness, as shown in Panel A. In the spinal cord, ketamine decreases arousal by blocking NMDA glutamate (Glu)–mediated nociceptive signals from peripheral afferent neurons in the dorsal-root ganglion to projecting neurons, as shown in Panel B.

Scientists Now Know How Sleep Cleans Toxins From the Brain

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Laura Lewis and her team of researchers have been putting in late nights in their Boston University lab. Lewis ran tests until around 3:00 in the morning, then ended up sleeping in the next day. It was like she had jet lag, she says, without changing time zones. It’s not that Lewis doesn’t appreciate the merits of a good night’s sleep. She does. But when you’re trying to map what’s happening in a slumbering human’s brain, you end up making some sacrifices. “It’s this great irony of sleep research,” she says. “You’re constrained by when people sleep.”

Her results, published today in the journal Science, show how our bodies clear toxins out of our brains while we sleep and could open new avenues for treating and preventing neurodegenerative diseases like Alzheimer’s.

When we sleep our brains travel through several phases, from a light slumber to a deep sleep that feels like we’ve fallen unconscious, to rapid eye movement (REM) sleep, when we’re more likely to have dreams. Lewis’ work looks at non-REM sleep, that deep phase which generally happens earlier in the night and which has already been associated with memory retention. One important 2013 study on mice showed that while the rodents slept, toxins like beta amyloid, which can contribute to Alzheimer’s disease, got swept away.

Lewis was curious how those toxins were cleared out and why that process only happened during sleep. She suspected that cerebrospinal fluid, a clear, water-like liquid that flows around the brain, might be involved. But she wasn’t sure what was unique about sleep. So her lab designed a study that measured several different variables at the same time.

Study participants had to lie down and fall asleep inside an MRI machine. To get realistic sleep cycles, the researchers had to run the tests at midnight, and they even asked subjects to stay up late the night before so people would be primed to drift off once the test began.

Lewis outfitted the participants with an EEG cap so she could look at the electrical currents flowing through their brains. Those currents showed her which stage of sleep the person was in. Meanwhile, the MRI measured the blood oxygen levels in their brains and showed how much cerebrospinal fluid was flowing in and out of the brain. “We had a sense each of these metrics was important, but how they change during sleep and how they relate to each other during sleep was uncharted territory for us,” she says.

What she discovered was that during non-REM sleep, large, slow waves of cerebrospinal fluid were washing over the brain. The EEG readings helped show why. During non-REM sleep, neurons start to synchronize, turning on and off at the same time. “First you would see this electrical wave where all the neurons would go quiet,” says Lewis. Because the neurons had all momentarily stopped firing, they didn’t need as much oxygen. That meant less blood would flow to the brain. But Lewis’s team also observed that cerebrospinal fluid would then rush in, filling in the space left behind.

“It’s a fantastic paper,” says Maiken Nedergaard, a neuroscientist at the University of Rochester who led the 2013 study that first described how sleep can clear out toxins in mice. “I don’t think anybody in their wildest fantasy has really shown that the brain’s electrical activity is moving fluid. So that’s really exciting.”

One big contribution of the paper is it helps show that the systems Nedergaard has been studying in mice are present and hugely important for humans too. “It’s telling you sleep is not just to relax,” says Nedergaard. “Sleep is actually a very distinct function.” Neurons don't all turn off at the same time when we're awake. So brain blood levels don't drop enough to allow substantial waves of cerebrospinal fluid to circulate around the brain and clear out all the metabolic byproducts that accumulate, like beta amyloid.

Sleep Apnea Changes the Shape of the Brain

The mental symptoms of sleep apnea are more serious than the temporary grogginess caused by drowsiness. During an apnea (Greek for “without breath”) the subject actually stops breathing, which starves the brain of oxygen. This duress, paired with chronic fatigue, can cause physical, measurable brain damage.

Researchers at UCLA compared the mammillary bodies—structures in the brain that are important in memory storage—of several adults suffering from sleep apnea with those of healthy people. They found that the bodies in the troubled sleepers were nearly 20% smaller than in their untroubled counterparts.

Furthermore, multiple studies have discovered a decrease in both gray and white matter in the brains of subjects with OSA. A study published in Sleep journal found significant reductions in gray matter concentrations in certain areas of the brain. This led principal investigator Doctor Seung Bong Hong of the Sungkyunkwan University School of Medicine in Seoul to conclude that “Poor sleep quality and progressive brain damage induced by OSA could be responsible for poor memory, emotional problems, decreased cognitive functioning and increased cardiovascular disturbances.” In 2008, a UCLA study found significant damage in the brain’s fiber pathways and structural alterations in its white matter, especially in areas that regulate mood, memory, and blood pressure.

How Sleep Clears the Brain

A mouse study suggests that sleep helps restore the brain by flushing out toxins that build up during waking hours. The results point to a potential new role for sleep in health and disease.

Scientists and philosophers have long wondered why people sleep and how it affects the brain. Sleep is important for storing memories. It also has a restorative function. Lack of sleep impairs reasoning, problem-solving, and attention to detail, among other effects. However, the mechanisms behind these sleep benefits have been unknown.

Dr. Maiken Nedergaard and her colleagues at the University of Rochester Medical Center recently discovered a system that drains waste products from the brain. Cerebrospinal fluid, a clear liquid surrounding the brain and spinal cord, moves through the brain along a series of channels that surround blood vessels. The system is managed by the brain’s glial cells, and so the researchers called it the glymphatic system.

The scientists also reported that the glymphatic system can help remove a toxic protein called beta-amyloid from brain tissue. Beta-amyloid is renowned for accumulating in the brains of patients with Alzheimer's disease. Other research has shown that brain levels of beta-amyloid decrease during sleep. In their new study, the team tested the idea that sleep might affect beta-amyloid clearance by regulating the glymphatic system. The work was funded by NIH’s National Institute of Neurological Disorders and Stroke (NINDS).

The researchers first injected dye into the cerebrospinal fluid of mice and monitored electrical brain activity as they tracked the dye flow through the animals’ brains. As reported in the October 18, 2013, edition of Science, the dye barely flowed when the mice were awake. In contrast, when the mice were unconscious — asleep or anesthetized — it flowed rapidly.

Changes in the way fluid moves through the brain between conscious and unconscious states may reflect differences in the space available for movement. To test the idea, the team used a method that measures the volume of the space outside brain cells. They found that this “extracellular” volume increased by 60% in the brain’s cortex when the mice were asleep or anesthetized.

The researchers next injected mice with labeled beta-amyloid and measured how long it lasted in their brains when they were asleep and awake. Beta-amyloid disappeared twice as quickly in the brains of mice that were asleep.

Glial cells control flow through the glymphatic system by shrinking and swelling. The hormone noradrenaline, which increases alertness, is known to cause cells to swell. The researchers thus tested whether the hormone might affect the glymphatic system. Treating mice with drugs that block noradrenaline induced a sleep-like state and increased brain fluid flow and extracellular brain volume. This result suggests a molecular connection between the sleep-wake cycle and the brain’s cleaning system.

The study raises the possibility that certain neurological disorders might be prevented or treated by manipulating the glymphatic system. “These findings have significant implications for treating ‘dirty brain’ diseases like Alzheimer’s,” Nedergaard says. “Understanding precisely how and when the brain activates the glymphatic system and clears waste is a critical first step in efforts to potentially modulate this system and make it work more efficiently.”

What Happens To The Body And Mind When Starvation Sets In?

It's an awful question, but it's the question of the moment. In what United Nations Secretary-General Ban Ki-moon has called a "war crime," thousands of people in Syria have been starving because both government and rebel blockades have kept food from reaching them. The town of Madaya has been under siege for months. U.N. relief staff members reported seeing elderly people, children, men and women who are little more than skin and bones. "Gaunt, severely malnourished, so weak they could barely walk and utterly desperate for the slightest morsel," Ban Ki-moon said, according to the U.N. News Service.

This is not just a problem in Syria. People suffer from extreme malnutrition all over the world in places where there is war, economic crisis, floods, drought and all manner of human suffering. About 1 in 9, or 795 million people in the world, suffers from undernourishment, according to the United Nations Food and Agricultural Organization.

And that's how starvation can begin — with undernourishment. People do not get enough calories to keep up with the body's energy needs. (Although starvation may be staved off if edibles are available that would not previously have been considered "food" — grass, leaves, insects or rodents.)

Over weeks and months, m alnutrition can result in specific diseases, like anemia when people don't get enough iron or beriberi if they don't get adequate thiamine.

A severe lack of food for a prolonged period — not enough calories of any sort to keep up with the body's energy needs — is starvation. The body's reserve resources are depleted. The result is substantial weight loss, wasting away of the body's tissues and eventually death.

When faced with starvation, the body fights back. The first day without food is a lot like the overnight fast between dinner one night and breakfast the next morning. Energy levels are low but pick up with a morning meal.

Within days, faced with nothing to eat, the body begins feeding on itself. "The body starts to consume energy stores — carbohydrates, fats and then the protein parts of tissue," says Maureen Gallagher, senior nutrition adviser to Action Against Hunger, a network of international humanitarian organizations focused on eliminating hunger. Metabolism slows, the body cannot regulate its temperature, kidney function is impaired and the immune system weakens.

When the body uses its reserves to provide basic energy needs, it can no longer supply necessary nutrients to vital organs and tissues. The heart, lungs, ovaries and testes shrink. Muscles shrink and people feel weak. Body temperature drops and people can feel chilled. People can become irritable, and it becomes difficult to concentrate.

Eventually, nothing is left for the body to scavenge except muscle. "Once protein stores start getting used, death is not far," says Dr. Nancy Zucker, director of the Duke Center for Eating Disorders at Duke University. "You're consuming your own muscle, including the heart muscle." In the late stages of starvation, people can experience hallucinations, convulsions and disruptions in heart rhythm. Finally, the heart stops.

How long does this take? There's great variation in the amount of time people can survive without food, depending on age, body weight, whether they have adequate water, and whether they have other underlying health issues. Mahatma Gandhi, in his nonviolent campaign for India's independence, survived for 21 days with only sips of water. One study found that hunger strikers in various parts of the world survived for up to 40 days.

"There's really no specific number of days people can survive," says Gallagher.

Theoretically, women might have a survival advantage because they have a greater percentage of stored body fat. But, says Zucker, no study proves that. The most thorough study of near starvation in humans was a 1950 study by Ancel Keys, "The Biology of Human Starvation," in which 36 volunteers — all male — were given a semi-starvation diet of 1,570 calories (the average man needs about 2,500 calories a day) for six months. It is from that study that nutrition scientists began to understand how the body reacts to food deprivation.

Children are smaller and have fewer body-fat stores to draw from. They fail much faster. "Children are at a much greater disadvantage," says Zucker. "With anorexia nervosa [an eating disorder characterized by an obsessive desire to lose weight by refusing to eat] we have to act a lot more quickly, because children and teens have fewer stores available they're growing and their metabolic needs are greater."

What is going on during starvation internally, biologically and metabolically, is invisible. But physical and behavioral changes are on display.

Both adults or children can act very much out of character. They might be irritable or apathetic or lethargic. "Starvation is a state of threat," says Zucker. And so people who are starving might act like a cornered animal, alert to any change around them and too quick to react to perceived threats. With a severe ongoing lack of food, people start doing things to ration food. "They eat more slowly. They might start shredding food to make it look like there is more. You take a piece of bread and shred it so you have a pile of bread crumbs," says Zucker.

The body attempts to protect the brain, says Zucker, by shutting down the most metabolically intense functions first, like digestion, resulting in diarrhea. "The brain is relatively protected, but eventually we worry about neuronal death and brain matter loss," she says. Just as the heart, lungs and other organs weaken and shrivel without food, eventually so does the brain. The concern for children is that their brains are still developing and any loss of function due to starvation could be permanent. But their brains are more plastic and might have a greater ability to bounce back, after they begin eating again.

"It's hard to know. Children suffer more steeply, but their recovery might be better. It might be a tie," says Zucker. "But adults and children alike can have permanent brain damage."

People who are in the throes of starvation look apathetic, lethargic — almost mechanical in their slow-motion reactions.

Starving people may not look as if they're in acute pain. But that doesn't mean they're not suffering. "I've seen kids who are not kids anymore. They're either irritated and crying, or they're apathetic and not playing," says Gallagher. "And their mothers are hopeless and not showing any signs of caring."

Treatment for someone who has been starved begins with a thorough medical exam. People might need hospitalization or antibiotics to treat underlying illnesses or infections. But therapeutic foods, like a fully nutritious peanut butter paste, dry skim milk and a wide set of vitamins and minerals, work well in the developing world.

And there's one curious observation that's been made. It's not clear why, but the problem of peanut allergies in the West is not an issue in sub-Saharan Africa and other areas where severe malnutrition is most common. "We haven't come across any allergic reactions to peanuts," says Gallagher.

Timing Is Everything

When a sleeping brain hears a word proved to be an important component in sleep learning. During slow wave sleep our brains alternate between “up states” and “down states” every half-second. During up states, the brain is highly active and interconnected — prime for learning.

“We looked how often we managed to hit these up-states with our word presentation, and what we found was that there is a clear dose-response curve: the more often you hit an up-state, the better the memory.”

In other words, people were more likely to correctly classify the words they heard during slow-wave peaks than the ones they heard during less-optimal periods of brain activity. To see what was happening inside the brain, a subgroup of participants performed the post-sleep memory test while being imaged with fMRI. As participants classified the new words they learned while sleeping, fMRI imaging showed that the language areas of the brain and hippocampus were activated.

It’s an indication that these structures allow for memory formation whether we’re awake or asleep, according to Züst.

Please remember, we are not able to give medical or legal advice. If you have medical concerns, please consult your doctor. All posted comments are the views and opinions of the poster only.

Anonymous replied on Mon, 05/24/2021 - 10:42pm Permalink

my friend has been in the hospital for a month .now he is at a acute center he has a bump on his head the size of a baseball. did the brain bleed cause this bump? will it go away? when will he wake up he is not in a coma any longer so why wont he open his eyes? I cant find his family and I cant get any answers because I am just a friend but he has nobody what can I do?

Anonymous replied on Thu, 05/20/2021 - 6:52pm Permalink

My father just died at Riverside hospital on the 30th of April. I'm his daughter, and I had to tell the wonderful nurse's it's time!! I held his hand after they gave him Morphine/Ativan to excavate his tube. He survived at the same hospital in Ohio. rectal..colon..liver..and Covid.
He fell onto the concrete, and they did a Petscan, and said he only had less than a tablespoon of blood, so since he didn't fall again, why did he suffer from a rebelled.

Alisha replied on Thu, 04/15/2021 - 9:57pm Permalink

I was kicked by a horse in the head and had five brain bleeds, inside and outside the brain and I’m lucky someone found me quickly or I’ll probably be dead. I’ve improved a lot thanks to therapy, but I’ve wondered am I doing well because they found me so quickly or is it because of my age? I’m 29 by the way and no they didn’t need to do surgery because I stopped bleeding

Brianna replied on Tue, 06/15/2021 - 6:49pm Permalink

Hi, I am glad to hear you have recovered well. Just wondering what therapies you used to recover in order for the bleeding to stop?

Anonymous replied on Wed, 09/02/2020 - 10:42pm Permalink

Hello my friend is in the hospital in ICU, she suffered a massive heart attack and cardiac arrest, shes 39! The drs said her Brain is still swollen and its been 7 days, we are all hoping shes ok and pulls through, anyone have anything or experience any thing close to this would be helpful. Im looking for direct answer no sugar coating please i can take it.

Anonymous replied on Thu, 07/30/2020 - 2:15am Permalink

If your brain was bleeding and it stopped but you clearly could see where the blood on the brain was does it just go away or do they have to remove the blood.

Anonymous replied on Wed, 06/03/2020 - 9:08pm Permalink

My dad passed away mon afternoon after having a terrible headache he was took into hospital had a ct scan which showed he had a minor bleed to the brain but was fine the hospital kept him in overnight so they could do another ct scan in morning but at 9.30 that morning while doing they’re checks he was unresponsive and unconscious they then noticed he had another massive bleed to brain which killed him , why did the hospital have to do another scan why did they not operate that night when they saw the minor bleed to the brain ?

mary replied on Wed, 06/03/2020 - 12:48pm Permalink

My Dad died of a
brain hemmorage that came out of absolutely nowhere 3 years ago. He suffered the worst kind of headache Father's Day morning.
Of course,we know now that that was the beginning of the end.
He died a horrible death a few days later. It was a horrible awful bad week,month,so forth so on.
I miss him bad.
Whoever you are,if you are dealing with now,I am sorry.
Keep the good memories alive,
Keep active in your life as much as you can,
and write down every little good memory,every detail,.this will help you later.
Chocolate is good right now,and you will find that you have memorized where the ice cream is at your local store.
Even years later,remember your dad happily.

Anonymous replied on Wed, 01/06/2021 - 7:13pm Permalink

I’m so sorry to hear about your father. My mother just called me and told me she was in the hospital. She had fallen for a couple of days and finally went to the hospital. The MRI showed a minor brain bleed. That’s all I know. She feels fine and they talked about some kind of a minor procedure but she’s almost 92.

Amy replied on Fri, 08/14/2020 - 6:56am Permalink

Thank you so much for this wonderful comment. My dad has survived his bleed, but we are not sure whether he will survive long-term or recover. Your comment made me find joy in the pain and uncertainty. Thank you x

Pedro Segura replied on Wed, 06/17/2020 - 9:45pm Permalink

I am sitting in my car outside the ER reading your post.thank you.

J perry replied on Tue, 05/19/2020 - 1:28pm Permalink

Hi I had a rta in nov and then surgery for a bleed on the brain 19th January followed by two further surgeries for infection and leaking csf fluid , last Friday I was c.t scanned finding a small bleed again , the hospital have said it’s small so no need for treatment but I’m worried it will get worse not better

Anonymous replied on Sun, 04/12/2020 - 10:49am Permalink

I am a 29 year old healthy woman they have told me. But for the past week I have been having a headache that resembles more of head pressure. It also comes with dizziness, rapid heart rate and and chest pain. When I am up and moving it seems to be worse than before sometimes. Never had any head injuries that I can recall. I have been to the ER twice. Two different ones. Had a head CT at both and both came back fine. Also experience some weakness or fatigue throughout the day. Should Inbe worries about a brain bleed or aneurisms if both CT scans came back clear?

Kelly replied on Thu, 07/16/2020 - 7:41pm Permalink

Hi I had the same thing. You must have a lot on your plate.. meaning maybe stress, kids, bf, husband, school, bills etc
Please feel free to write back.. I had the exact same thing and I suffer with migraines

Linda Fredrick replied on Tue, 06/16/2020 - 9:57am Permalink

Please have a neurologist do a MRI /MRA to make sure yo dont have an AVM (malformed artery vein connection) which can rupture and bleed. CTs dont always pick them up, or better yet a cerebroarteriogram which show all of rhe vessels. Most ER docs aren't that skilled. I would say a neurologist or neuro surgeon would be best to start with. My hubby. now is physically disabled,and dependent, following a rupture that nearly killed him.

Anonymous replied on Sat, 04/11/2020 - 4:10pm Permalink

Nearly 30 yrs. ago, I received a CHI/TBI due to being in an auto accident. I was 21.When the police told my mom, she called the hospital and an ER nurse, told her that there was swelling and bleeding on the brain. What kind of medications and procedures, would they have used in the ER back then, decades ago.

Anonymous replied on Tue, 03/17/2020 - 12:24am Permalink

Hope u r a better dr than the one's I come in contact with. This is the 2nd time I was released with a brain injury. Confused and agitated and 3 day's later I can't stand up for long and when I tried to sweep it kept smelling like blood in my nose. Also keep feeling pressure in my sinus area

Kat replied on Tue, 01/07/2020 - 7:48am Permalink

Can anyone who has experience with a loved one going through this after prescribed blood thinners?

Liv replied on Mon, 02/08/2021 - 1:58pm Permalink

Yesterday I found my nan unconscious in her bed (must’ve happened in her sleep). Today we found out she won’t be coming home. She was on blood thinners, don’t know if it caused it but she sadly won’t be with us anymore soon. RIP to those who’ve lost loved ones.

Mary McGinn replied on Thu, 01/30/2020 - 10:16am Permalink

My brother is on Eliquis currently in ICU on vent with a brain bleed. Did you receive info on your question?

Susan replied on Wed, 01/29/2020 - 1:32am Permalink

Yes my dad had 4 blood thinners after a heart surgery last week and two days later he is in the hospital with a brain bleed stroke.

engie replied on Mon, 12/23/2019 - 3:13pm Permalink

what happens after? can you be fully functional after recovery?

Yolanda Dukes replied on Mon, 08/12/2019 - 11:05pm Permalink

Bilateral convexity subdural hematomas, larger on the left. The left subdural hematoma measures 9 mm in thickness and exerts mass effect on the adjacent brain parenchyma. The right subdural hematoma measures 3 mm. There is 2 to 3 mm of rightward midline shift. No downward herniation. The ventricular size is normal. Diffusion abnormality and susceptibility associated with blood products. this what they said about my MRI with contras, this showed up two months after my car crash, should I be worried since it happen so late after my accident? none of the other ct showed this before and I had 4 ct before this one. should I be worried

Erick replied on Fri, 12/06/2019 - 7:08pm Permalink

Hi Yolanda, did you ever find a resolution to this? My dad was/is under a similar situation, where he was diagnosed with a subdural hematoma months after a car collision. He took steroids for 2 weeks and his subdural hematoma was greatly diminished in size, his midline shift has gone from 7mm to 2mm, but the slow brain-bleed has continued, so I'm curious if you're also struggling with the same. Hopefully you've been able to heal completely, and if so, I'd be curious to know what was done in your situation

Violet Spence replied on Tue, 10/08/2019 - 1:36pm Permalink

I was told, that I have bleeding vessels in the back of my brain. I have to see a neurosurgeon. What will he do?

Anonymous replied on Wed, 02/26/2020 - 6:09am Permalink

I have a small bleed in the brain which is causing me headaches i have had them for about 8 weeks i have to see a nerosurgeon what will he do

Carole westgart. replied on Tue, 06/25/2019 - 3:29pm Permalink

My son 30yrs ago had a very bad fracture of the skull. Over a period of years he has suffered two brain bleeds. He can’t smell anything. Now drinks to much. Is that a worry

Nidhi replied on Sun, 06/09/2019 - 9:25am Permalink

Sir my mamiji fell from a bike. She has got severe head injury. Her surgery was done after 48 hours. In surgery, her front forehead bones were removed and kept in stomach so that brain can expand. After a day, in her CT scan it shows there is bleeding inside the brain and platelets less. She is unconsciousness from five days and able to breath much on ventilator. I want to know what are the chances of her survival. I am waiting for reply as she is in hospital right now fighting for life in PGI Chandigarh.

Anita E. replied on Fri, 10/25/2019 - 12:16am Permalink

I am praying for your family in this time of turmoil, may God give you peace, wisdom & understanding.♡

Christine Conley replied on Sun, 04/28/2019 - 7:44am Permalink

My sister had a brain bleed and was unconscious for a 6 hours waking a few times, she was moved to a neurology hospital where on arrival she became responsive answering the Drs questions. She had one brain scan, and the neuro team were going to give her another. Within 10 minutes of being responsive she started having seizures. She was operated on and found that another bleed had occurred and her brain had been too badly damaged and she died later on. Is this normal?

Sharon M replied on Wed, 04/10/2019 - 1:37pm Permalink

My sister had a tumor removed from her pituitary gland. The tumor was bigger than thought, and she had a brain bleed, fluid and her brain was swelling. Now because of the location of the blood, she can't open her eyes. She has a drain in and will put in a shunt later this week. I know every one is different and our bodies are different and react different. But how long will it take for this blood to be drained so she can open her eyes?

Barbara replied on Sun, 03/31/2019 - 4:09pm Permalink

My 2 month old grandaughter has been admitted to the hospital my daughter said she stopped breathing after a bottle and nappy change she phoned for an abulance while her husband gave cpr the paramedics came and put a tube down her throat she started breathing again she was given a scan of her brain to rule out meningitis but they were told she has a bilateral brain bleed how has this happened why has this happened

Hazel replied on Tue, 03/19/2019 - 2:53pm Permalink

Victoria replied on Thu, 03/07/2019 - 10:36am Permalink

I was admitted to Royal London hospital on Monday with a suspected bleed on the brain. They wanted to admit me for a Lumbar puncture and MRI. As the royal london is 2 hours from my home I asked if i could be transferred to a hospital near my home. They agreed, discharged me and said that I should take a letter they gave me to my GP for the referral to the hospital nearer my home. The hospital have my referral and it was sent as urgent. My scan is now scheduled for anything up to 4 weeks. Surely this is too long for a suspected brain bleed? Any advice would be appreciated.

Rivin replied on Tue, 03/19/2019 - 3:47pm Permalink

Going through this as we speak. My mother in law was sent to emergency by her doctor over two weeks ago with a suspected stroke. They did not do a cat scan and said she was just old and confused and sent her home. Two weeks later now her doctor made a ‘scheduled’ CT scan, they sent her straight to ER and she is currently (while I type this) having surgery to drain the old blood from two weeks ago. Slow brain bleed She most likely will have permanent damage from pressure and lack of octogenarian to parts of her brain.

Don’t take no for an answer. Keep going to emergency until the do a scan. It’s not worth waiting. If it’s a suspected bleed. the sooner you catch it, the better.

We don't live in the same city, or I would have pushed for the scan two weeks ago that’s why we came now! Hope you get help.

Montgomery replied on Mon, 10/05/2020 - 9:33am Permalink

My 11yr died Saturday from a brain bleed they didn't do ctscan until 6 hrs after being there she had all the symptoms but they didn't care.

Bradley replied on Thu, 03/07/2019 - 6:04am Permalink

Hi. I was in a car crash over 6 months ago I had a minor bleed on the brain. I was told I was fine and sent home. I’ve been suffering with severe headaches ever since is this a sign of blood clotting on the brain? Severe headaches and every now and then a weird pain in the back of my left leg ?

Sissy Robertson replied on Thu, 03/07/2019 - 12:55am Permalink

My mom had a brain hemorrhage and a stroke and for some reason had an infection that the hospital could not have her find they eventually pretty much kicked her out of the hospital afyer 2 months into a nursing home and within two weeks she had passed away in my opinion I think she had sepsis and they never tested her for it could I be right on that topic

Josimar replied on Sun, 02/24/2019 - 5:57pm Permalink

My mother passed away and I already talk to the doctor about how she passed away. They said she was brain dead by bleeding in the head but idk how that can occur they didn't say if she fell or want do they even know what exactly happen because she was staying with her bf that is abusive. I need answers it really hurts I feel so lost

John replied on Wed, 02/27/2019 - 1:51am Permalink

My heart hurts with you. I feel sad about your loss and especially about how little you know about how your mother died.
Personally, I would feel lost most of the time if I didn't have someone strong and kind who is with me and helping me. hymnsradio has given me so many answers. I don't know if it might help?

Pieter replied on Sun, 02/24/2019 - 2:27pm Permalink

I have concussion now for the 6 th time due to rugby can't remember anything from the match is it possibly bleeding on the brain

Amy replied on Fri, 01/18/2019 - 6:46pm Permalink

I have a very good friend that I found out had a recent sudden brain bleed, was in icu and not expected to make it, found out that he did but can not see or speak but is aware of his surrounding s, don't think I should go see him, don't know anything about him except what another friend of ours tells me that this guy's wife tells him I would like to see him eventually, but have also heard that he may end up in a nursing home, kiss of death, how can I be a friend to him and find out if his wife is telling the truth to our friends? ?

Chad replied on Sat, 05/08/2021 - 11:20am Permalink

A rule of thumb that I always try to use is don't let somebody else's views be the sole defector and how you feel about somebody. For example, I had a girlfriend who probably been dating for about 2 months. She came in and moved in with me and it was a long-distance relationship. Like I said only been together for maybe two to three months. My mom called me and said hey did you know that your girlfriend tried to steal from the gas station. I said no I hadn't heard anything about it, she just left to go to Dollar General and told my mom thanks you know for letting me know. So I got up and walk to Dollar General found my girlfriend straight out after did you try to steal something from the gas station. She got mad at me really mad at me no do you honestly think I would do something like that and I'd let her know right then no I don't but my mom called me saying that the lady at the gas station said that she caught you trying to steal and of course if I thought that you would do that I wouldn't have come and asked you I respect you enough to come and ask you and not let other people make me feel a certain way or you know I said if I didn't respect you I wouldn't have asked you if I would have just thought that it was true. That's how I've always looked at situations but yourself and their shoes and you know what people get mad at people and they make up lives to ruin their reputation because they have nothing better to do like moving on or letting go. Some people can't take themselves out of the problems and put the problem on the table and talk to each other about it so that it can get solved. I myself have this problem at times but when things like that happen they try to ruin their reputation. So I would go talk to the guy and make up your own mind. See what he matches or what he says if it makes sense or more sense over what they say that he's done. Also find out about this guy from his past reputation before it all started people is good values and a kind heart. I mean we all make mistakes but people that are genuine like that 99% of the time it's not going to be true and the problem is and is it has happened to me there too good of a person to stand up for themselves because I know it's going to start a bigger fight and they would rather let other people think whatever and try and keep somewhat of the peace. I hope this helped you man. I know when I was in this situation and I was that person. I really wish the people that knew the real me would have spoken up.

Anita E. replied on Fri, 10/25/2019 - 12:26am Permalink

Honey, it's not for you to find out. Perhaps the family is protecting their own, and themselves, it's a difficult time for each of you. Every processes differently. Be
understanding, patient, kind.

Shaz replied on Wed, 06/26/2019 - 4:05pm Permalink

Go see him for yourself
. Life

Go see him for yourself. Life is too short for questions.

Francine replied on Mon, 01/07/2019 - 11:41am Permalink

mom fell, split her head open, required 6 staples, had a concussion and wound up with a brain bleed. as the blood receeded she started having 2 incidents of multiple strokes. What damage did the brain bleed cause.

Jackie Eshleman replied on Wed, 02/13/2019 - 4:56pm Permalink

Husband had a fall, head wound, stitches and two small brain bleeds.
What precautions should he take during recovery

Deneace replied on Fri, 12/21/2018 - 2:33am Permalink

Please can someone help me, my father has had his second craniotomy surgery in one month. He has a spontaneous bleeding from his brain, no one knows the cause? In 3 days he has lost 300 mls of fluid from his brain that’s in a drain attached to his head. He has confusion, disoriented. He’s 80 y/o. He had a stroke as well. He is in icu and I’m his daughter and I don’t feel I’m getting straight answers about his condition. Today has been day 5 and he’s still bleeding into the drain. Can anyone tell me when this will stop.

Lina replied on Sat, 07/20/2019 - 10:00pm Permalink

I am so very sorry you went through this. I hope he made it out okay. Sending prayers. God bless!

Red Dorsey replied on Sat, 12/29/2018 - 4:54pm Permalink

We are in a similar situation with my sister in law no straight answers. I found your comment on this website I’m doing research possibly ask about the bloodwork look at the MRI pictures or whatever they are Doing to help him and why. We pray for all of us

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