Chapter 10. Biological Rhythms and Sleep
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By Stephani Sutherland Scientists have long known that once we nod off, certain memories grow stronger. One recent theory suggests that forgetting, too, is an essential function of sleep [see “Sleep's Secret Repairs,” by Jason Castro; Scientific American Mind, May/June 2012]. Researchers now suspect that post-traumatic stress disorder (PTSD) may emerge from flaws in sleep's forgetting process. Two studies presented at the 2012 meeting of the Society for Neuroscience in New Orleans indicate that sleep might offer a window of opportunity for weakening memories and providing relief from lingering reminders of trauma. Neuroscientists believe that during sleep, a memory-elimination routine cleans out obsolete information by physically weakening synapses, the junctions between communicating neurons. Gina Poe, a neuroscientist at the University of Michigan, found in mice that for synapses to lose strength, levels of the neurotransmitter noradrenaline must drop. Noradrenaline levels typically fall during REM sleep in rodents and humans, but in people with PTSD the amount stays high throughout sleep. Normalizing noradrenaline with pharmaceuticals, Poe says, “could absolutely be a key target to actually cure PTSD through normal sleep.” In a separate experiment, researcher Asya Rolls of Stanford University hijacked memory remodeling in sleeping mice to make a traumatic association less scary. Rolls and her colleagues conditioned mice to fear the scent of jasmine flowers by pairing the smell with a foot shock. When the mice slept, they released a puff of jasmine. Under normal circumstances, the smell would reactivate and bolster the memory, a process that requires newly made structural proteins. The researchers gave some mice a drug that prevented the manufacture of these building blocks in a key fear-memory area. When these mice woke up, they no longer responded to the odor with fearful behavior, indicating that the memory had been successfully disrupted. The findings might someday translate to a new kind of sleep-based therapy in people whose traumatic experiences are tied to specific sounds and smells—such as the noise of a bomb going off—that can be presented to their sleeping brain. © 2013 Scientific American
Barry Gordon, professor of neurology and cognitive science at the Johns Hopkins University School of Medicine, replies: We are aware of a tiny fraction of the thinking that goes on in our minds, and we can control only a tiny part of our conscious thoughts. The vast majority of our thinking efforts goes on subconsciously. Only one or two of these thoughts are likely to breach into consciousness at a time. Slips of the tongue and accidental actions offer glimpses of our unfiltered subconscious mental life. The intrusive thoughts you may experience throughout the day or before bed illustrate the disconcerting fact that many of the functions of the mind are outside of conscious control. Whether we maintain true control over any mental functions is the central debate about free will. Perhaps this lack of autonomy is to be expected as the foundations for almost all the mind's labors were laid long before our ancestors evolved consciousness. Even deliberate decisions are not completely under our power. Our awareness only sets the start and the end of a goal but leaves the implementation to unconscious mental processes. Thus, a batter can decide to swing at a ball that comes into the strike zone and can delineate the boundaries of that zone. But when the ball comes sailing through, unconscious mental functions take over. The actions required to send him to first base are too complex and unfold too quickly for our comparatively slow conscious control to handle. © 2013 Scientific American
By Rachel Ehrenberg A computer can decode the stuff of dreams. By comparing brain activity during sleep with activity patterns collected while study participants looked at certain objects, a computer learned to identify some contents of people’s unconscious reveries. “It’s striking work,” says cognitive psychologist Frank Tong of Vanderbilt University in Nashville, who was not involved in the research. “It’s a demonstration that brain activity during dreaming is very similar to activity during wakefulness.” The work, reported April 4 in Science by Japanese researchers led by Yukiyasu Kamitani of Advanced Telecommunications Research Institute International, adds to somewhat scant knowledge of how the brain constructs dreams, says Tong. The research could lead to a better understanding of what the brain does during different states of consciousness, such as those experienced by some coma patients. Dreams are a bit of a black box and difficult to study. Experiments with mice have revealed aspects of sleep and dreaming, such as how the experiences contribute to forming memories. But a mouse can’t tell you what it dreamed about. And the sleep stage that’s richest in dreams — REM sleep — typically kicks in about 90 minutes after a person conks out, making it time consuming to gather data on dreams. The noisy fMRI brain scanning machine doesn’t help. To skirt these experimental issues, the researchers recorded brain activity in three adult male volunteers during the early stages of sleep. After the subjects had dozed off, they were repeatedly awakened and asked for detailed reports on what they had seen while sleeping. In an example, one participant stated: “Well, there were persons, about three persons, inside some sort of hall. There was a male, a female and maybe like a child. Ah, it was like a boy, a girl and a mother. I don't think that there was any color.” © Society for Science & the Public 2000 - 2013
by Gisela Telis Insomniacs desperate for some zzzs may one day have a safer way to get them. Scientists have developed a new sleep medication that has induced sleep in rodents and monkeys without apparently impairing cognition, a potentially dangerous side effect of common sleep aids. The discovery, which originated in work explaining narcolepsy, could lead to a new class of drugs that help people who don't respond to other treatments. Between 10% and 15% of Americans chronically struggle with getting to or staying asleep. Many of them turn to sleeping pills for relief, and most are prescribed drugs, such as zolpidem (Ambien) and eszopiclone (Lunesta), that slow down the brain by binding to receptors for GABA, a neurotransmitter that's involved in mood, cognition, and muscle tone. But because the drugs target GABA indiscriminately, they can also impair cognition, causing amnesia, confusion, and other problems with learning and memory, along with a number of strange sleepwalking behaviors, including wandering, eating, and driving while asleep. This has led many researchers to seek out alternative mechanisms for inducing sleep. Neuroscientist Jason Uslaner of Merck Research Laboratories in West Point, Pennsylvania, and colleagues decided to tap into the brain's orexin system. Orexin (also known as hypocretin) is a protein that controls wakefulness and is missing in people with narcolepsy. Past studies successfully induced sleep by inhibiting orexin, but had not looked into its effects on cognition. The researchers developed a new orexin-inhibiting compound called DORA-22 and confirmed that it could induce sleep in rats and rhesus monkeys as effectively as the GABA-modulating drugs. © 2010 American Association for the Advancement of Science.
Link ID: 17994 - Posted: 04.05.2013
By ANAHAD O'CONNOR Doctors have plenty of good reasons to persuade people with sleep apnea to get it treated. The widespread disorder causes disruptions in breathing at night, which can ruin sleep and raise the likelihood of problems like obesity and fatigue. The standard treatment for the condition, a mask worn at night that delivers continuous positive airway pressure, or CPAP, significantly improves apnea, even though many people don’t like to wear it. But the mask may do more than restore normal breathing at night. Some research suggests it reduces inflammation, benefiting overall health. Many studies have looked at the link between sleep apnea and high levels of inflammatory markers. To get a clearer picture of the connection, a team of researchers recently carried out a meta-analysis that pooled data from two dozen trials involving over 1,000 patients. It was published last month. The data suggested that treating apnea with CPAP significantly reduces levels of two proteins associated with inflammation: tumor necrosis factor and C-reactive protein, or CRP. Sleep apnea is a risk factor for several severe chronic conditions like Type 2 diabetes and heart disease. It’s not clear whether apnea helps drive the development of these disorders or vice versa. But reducing inflammation may be one way in which treatment with CPAP reverses some of the long-term consequences of the sleep disorder. THE BOTTOM LINE: Treating sleep apnea with positive airway pressure helps to lower systemic inflammation, which might prevent some of the other problems associated with the disorder. Copyright 2013 The New York Times Company
By Markham Heid As if physical fatigue and a foggy brain weren't bad enough, restless nights may also harm your heart. A new multi-year study published in the European Heart Journal finds evidence of a substantial link between insomnia and the risk of heart failure. For more than 11 years, a study team from several Scandinavian universities tracked the sleeping habits and heart failure rates of more than 50,000 men and women. The researchers focused on the three major hallmarks of insomnia: trouble falling asleep, trouble staying asleep, and waking up still feeling fatigued. Unfortunately, the results of their analysis are enough to keep a person up at night: Among participants who experienced just one of those symptoms "occasionally" or "often," rates of heart failure increased 5% and 14%, respectively, compared to those who didn't struggle with sleep. But for those who experienced all three symptoms frequently, heart failure rates more than tripled, says study co-author Lars Laugsand, PhD, of the Norwegian University of Science and Technology. "Insomnia is a disorder marked by hyperarousal," Laugsand says. So instead of the restful state you should experience while sleeping, insomnia increases activity in your sympathetic nervous system, which in turn releases a flood of stress hormones into your bloodstream. This hormonal surge appears to boost blood pressure, which explains why periods of insomnia can make you feel like your heart is pounding or your body is overheating. © 2013 NBCNews.com
Link ID: 17971 - Posted: 04.01.2013
By Melissa Healy, Listening in on the electrical currents of teenagers’ brains during sleep, scientists have begun to hear the sound of growing maturity. It happens most intensively between the ages of 12 and 161 / 2: After years of frenzied fluctuation, the brain’s electrical output during the deepest phase of sleep — the delta, or slow-wave phase, when a child’s brain is undergoing its most restorative rest — becomes practically steady. That reduced fluctuation in electroencephalogram signals appears to coincide with what neuroscientists have described as major architectural changes in the brain that pave the way for cognitive maturity. While babies, toddlers and young children are taking in and making sense of the world, their brain cells are wiring themselves together willy-nilly, creating super-dense networks of interwoven neurons. But as we reach and progress through adolescence, neuroscientists have observed, a period of intensive “synaptic pruning” occurs in which those networks are thinned and the strongest and most evolutionarily useful remain. In a study published last week, scientists from the University of California at Davis say they believe the slowed fluctuations observed during the delta phase of teens’ sleep may be evidence of that pruning process at work. And since major mental illnesses such as schizophrenia appear to take root during adolescence, the authors of the study say the changing architecture of sleep may offer clues as to how and when mental illness sets in. © 1996-2013 The Washington Post
By Gary Stix A little shuteye refreshes. Right, but what does that really mean? Not talking here about leaping out of bed ready for a five-mile run upon awakening, but rather about what’s happening at the level of individual brain cells deep inside your head. A new study by R. Douglas Fields, a pioneer in researching out-of-the-mainstream brain areas and neural activity, holds one promising suggestion. Fields’s team at the National Institutes of Child Health and Development in Bethesda, Maryland, built on an earlier observation that during sleep (or even when just chilling out), neural signals travel the “wrong way” in cells of a critical region of the hippocampus, the brain structure involved with forming some types of new memories. The new study by Fields demonstrates, in a lab dish, that this reverse trafficking functions as a form of “editing,” a physical paring back of inessential parts of a brain cell to ensure that you don’t forget what you learned the previous day. Specifically, electrical signals in the CA1 area of the hippocampus reverse direction like the opposite flow of cars during the evening rush hour. The spiking electrical pulses move up instead of down the long extensions of nerve cells known as axons. The train of spikes pass through the cell body where the nucleus resides before reaching the ends of thousands of tiny branching tendrils called dendrites. © 2013 Scientific American
Link ID: 17938 - Posted: 03.23.2013
Nursing home residents who take a class of sleep medications that includes Lunesta and Ambien may be at higher risk for hip fractures compared with those who do not take these nonbenzodiazepine hypnotic drugs, according to a Harvard Medical School study. The study involved more than 15,000 nursing home residents who were on average 81 years old and were documented by Medicare to have had a hip fracture between July 2007 and December 2008. Nearly 11 percent of the residents with hip fractures took these drugs. Residents who took the prescription sleep medications were 66 percent more likely to sustain a hip fracture than those who did not. The risk was greater among new users of the medications and those suffering mild to moderate mental and physical decline. Those who took the medication for less than two months were more than twice as likely to fracture their hip, the study found. Nonbenzodiazepenes have been known to alter memory, attention, and balance, which may be why there is a greater risk of physical injury when taking the medication, the researchers wrote. Based on the findings, nursing home staff should try to treat sleep problems using nondrug strategies first, such as increased daytime activity and discouraging daytime napping, according to the researchers. © 2012 NY Times Co
by Jennifer Viegas Roosters are genetically programmed to crow with the dawn, finds a new study that could also help to explain why dogs bark and cats meow. Previously it was unknown if crowing roosters were simply reacting to their environment. “‘Cock-a-doodle-doo’ symbolizes the break of dawn in many countries,” Takashi Yoshimura of Nagoya University, who worked on the study, was quoted as saying in a press release. “But it wasn’t clear whether crowing is under the control of a biological clock or is simply a response to external stimuli.” That’s because things like a car’s headlights can set a rooster off too, as anyone who has lived near these birds knows. To solve the mystery, Yoshimura and colleagues kept roosters under round-the-clock dim lighting. This didn’t deter the roosters. No matter what, they kept crowing each morning just before dawn. The researchers say this is proof that the vocalizing is entrained to a circadian rhythm. In short, the roosters are genetically programmed to crow at a certain time. At some point, the rising sun set the roosters’ internal clock, so now they crow every 24 hours. Most animals, and plants too, have such an internalized timing mechanism. That’s why we tend to eat, sleep, exercise and more at around the same times. By consciously being aware of the schedule, our body has a chance to adapt to it, so well-functioning circadian rhythms are often tied to good health. © 2013 Discovery Communications, LLC.
Keyword: Biological Rhythms
Link ID: 17919 - Posted: 03.19.2013
By TARA PARKER-POPE The best path to a healthy weight may be a good night’s sleep. For years researchers have known that adults who sleep less than five or six hours a night are at higher risk of being overweight. Among children, sleeping less than 10 hours a night is associated with weight gain. Now a fascinating new study suggests that the link may be even more insidious than previously thought. Losing just a few hours of sleep a few nights in a row can lead to almost immediate weight gain. Sleep researchers from the University of Colorado recruited 16 healthy men and women for a two-week experiment tracking sleep, metabolism and eating habits. Nothing was left to chance: the subjects stayed in a special room that allowed researchers to track their metabolism by measuring the amount of oxygen they used and carbon dioxide they produced. Every bite of food was recorded, and strict sleep schedules were imposed. The goal was to determine how inadequate sleep over just one week — similar to what might occur when students cram for exams or when office workers stay up late to meet a looming deadline — affects a person’s weight, behavior and physiology. During the first week of the study, half the people were allowed to sleep nine hours a night while the other half stayed up until about midnight and then could sleep up to five hours. Everyone was given unlimited access to food. In the second week, the nine-hour sleepers were then restricted to five hours of sleep a night, while the sleep-deprived participants were allowed an extra four hours. Copyright 2013 The New York Times Company
When the mind is at rest, the electrical signals by which brain cells communicate appear to travel in reverse, wiping out unimportant information in the process, but sensitizing the cells for future sensory learning, according to a study of rats conducted by researchers at the National Institutes of Health. The finding has implications not only for studies seeking to help people learn more efficiently, but also for attempts to understand and treat post-traumatic stress disorder — in which the mind has difficulty moving beyond a disturbing experience. During waking hours, electrical signals travel from dendrites — antenna-like projections at one end of the cell — through the cell body. From the cell body, they then travel the length of the axon, a single long projection at the other end of the cell. This electrical signal stimulates the release of chemicals at the end of the axon, which bind to dendrites on adjacent cells, stimulating these recipient cells to fire electrical signals, and so on. When groups of cells repeatedly fire in this way, the electrical signals increase in intensity. Dr. Bukalo and her team examined electrical signals that traveled in reverse?from the cell’s axon, to the cell body, and out its many dendrites. The reverse firing, depicted in this diagram, happens during sleep and at rest, appearing to reset the cell and priming it to learn new information. It was previously known that, during sleep, these impulses were reversed, arising from waves of electrical activity originating deep within the brain. In the current study, the researchers found that these reverse signals weakened circuits formed during waking hours, apparently so that unimportant information could be erased from the brain. But the reverse signals also appeared to prime the brain to relearn at least some of the forgotten information. If the animals encountered the same information upon awakening, the circuits re-formed much more rapidly than when they originally encountered the information.
US researchers have found a link between working night shifts and the risk of ovarian cancer. A study of more than 3,000 women suggested that working overnight increased the risk of early-stage cancer by 49% compared with doing normal office hours. One possible explanation was disruption of the sleep hormone melatonin, the researchers said. But experts warned more work was needed and there might be other explanations. It does however follow an earlier association made between shift work and breast cancer. The International Agency for Cancer Research has previously identified working shift patterns that disrupt the body's natural "clock" as a probable cause of cancer. In the latest investigation, researchers looked at 1,101 women with advanced ovarian cancer, 389 with borderline or early disease and 1,832 women without the condition. Overall, a quarter with advanced cancer said they had worked night shifts, compared with a third of those with borderline disease and one in five of the control group. Analysis of the data showed a 24% increased risk of advanced cancer and 49% increased risk of early-stage disease for night workers compared with those who worked during the day. But the results were only significant for women over the age of 50, the researchers reported in Occupational and Environmental Medicine. And the risk did not seem to increase for those who had worked night shifts for the longest. BBC © 2013
By NICHOLAS BAKALAR Insomnia may be linked to an increased risk of heart failure, according to a large new study, and the more insomnia symptoms, the greater the risk. The study, published last week in The European Heart Journal, used questionnaires to gather data on difficulty falling asleep, difficulty staying asleep, and waking unrefreshed among more than 54,000 Norwegian adults in a population-wide health survey. All were free of heart disease at the start of the study; there were 1,412 cases of heart failure over an average of 11 years of follow-up. After controlling for numerous health, behavioral and demographic factors, the researchers found that having one symptom of insomnia was associated with a 17 percent increase in the risk of developing heart failure. Having two symptoms increased the chances by 92 percent, and having all three nearly tripled the risk. Insomnia was a risk independent of other cardiovascular risks, and the authors suggest that chronic insomnia leads to higher blood pressure and higher heart rate, known risk factors for heart failure. “We cannot claim that insomnia is causing heart failure,” said the lead author, Lars E. Laugsand, a postdoctoral fellow at the Norwegian University of Science and Technology. “But observational studies are all going more or less in the same direction — showing that insomnia may play a role in heart problems.” Copyright 2013 The New York Times Company
Link ID: 17895 - Posted: 03.12.2013
By David Robson, The dreams of Mary Shelley, author of “Frankenstein,” involved a pale student kneeling beside a corpse that was jerking back to life. Paul McCartney’s contained the melody of “Yesterday,” while director James Cameron’s inspired the “Terminator” films. With their eerie mixture of the familiar and the bizarre, it is easy to look for meaning in these nightly wanderings. But why do our brains take these journeys, and why do they contain such outlandish twists and turns? Unfortunately for armchair psychoanalysts, Sigmund Freud’s attempts to interpret dreams remain hotly disputed. Nevertheless, neuroscientists and psychologists have recently made big strides in understanding the way the brain builds our dreams and the factors that shape those curious stories. Along the way, they have found startling hints that our use of technology may be permanently changing the nature of this fundamental human experience. Anyone who has ever awakened feeling amazed by a dream, only to forget its contents before reaching the shower will understand the difficulties of studying such an ephemeral state of mind. Some of the best attempts to catalogue dream features either asked participants to jot them down as soon as they woke up or had volunteers sleep in a lab where they were awakened and immediately questioned at intervals in the night. © 1996-2013 The Washington Post
Link ID: 17894 - Posted: 03.12.2013
by Elizabeth Norton The prospect of undergoing surgery while not fully "under" may sound like the stuff of horror movies. But one patient in a thousand remembers moments of awareness while under general anesthesia, physicians estimate. The memories are sometimes neutral images or sounds of the operating room, but occasionally patients report being fully aware of pain, terror, and immobility. Though surgeons scrupulously monitor vital signs such as pulse and blood pressure, anesthesiologists have no clear signal of whether the patient is conscious. But a new study finds that the brain may produce an early-warning signal that consciousness is returning—one that's detectable by electroencephalography (EEG), the recording of neural activity via electrodes on the skull. "We've known since the 1930s that brain activity changes dramatically with increasing doses of anesthetic," says the study's corresponding author, anesthesiologist Patrick Purdon of Massachusetts General Hospital in Boston. "But monitoring a patient's brain with EEG has never become routine practice." Beginning in the 1990s, some anesthesiologists began using an approach called the bispectral (BIS) index, in which readings from a single electrode are connected to a device that calculates, and displays, a single number indicating where the patient's brain activity falls on a scale of 100 (fully conscious) to zero (a "flatline" EEG). Anything between 40 and 60 is considered the target range for unconsciousness. But this index and other similar ones are only indirect measurements, Purdon explains. In 2011, a team led by anesthesiologist Michael Avidan at the Washington University School of Medicine in St. Louis, Missouri, found that monitoring with the BIS index was slightly less successful at preventing awareness during surgery than the nonbrain-based method of measuring exhaled anesthesia in the patient's breath. Of the 2861 patients monitored with the BIS index, seven had memories of the surgery, whereas only two of 2852 patients whose breath was analyzed remembered anything. © 2010 American Association for the Advancement of Science.
By David Brown, Hey, you, yawning in your cubicle at 2 in the afternoon. Your genes feel it, too. A new study, paid for by the U.S. Air Force but relevant for anyone with a small child, a large prostate or a lot on the mind, is helping illuminate what’s happening at the genetic level when we don’t get enough sleep. It turns out that chronic sleep deprivation — in this experiment, less than six hours a night for a week — changes the activity of about 700 genes, which is roughly 3 percent of all we carry. About one-third of the affected genes are ramped up when we go with insufficient sleep night after night. The other two-thirds are partially suppressed. Hundreds of “circadian genes” whose activity rises and falls each day abruptly lose their rhythm. Among the genes disturbed by sleep deprivation are ones involved in metabolism, immunity, inflammation, hormone response, the expression of other genes and the organization of material called chromatin on chromosomes. These changes may help explain how inadequate sleep alters attention and thinking and raises the risk for illnesses such as diabetes and coronary heart disease. “The findings will identify some of the pathways linking insufficient sleep and negative health outcomes,” said Derk-Jan Dijk, a physiologist at the University of Surrey in England, who led the study. “But how these things ultimately lead to obesity or diabetes is an unanswered question at this moment in time.” © 1996-2013 The Washington Post
Steve Connor Physical exhaustion can occur when the brain – as well as the muscles – grows tired according to a study that sheds fresh light on the role played by the mind in determining endurance levels. Scientists have found that a key neurotransmitter in the brain, which controls signalling between nerve cells, can determine whether someone feels exhausted following physical exercise or after taking anti-depressant drugs such as Prozac. Although levels of serotonin rise during exercise, which provides a psychological boost and “feel-good” factor, it can also result in a widespread central fatigue that ultimately leads to someone feeling exhausted and unable to carry on, scientists found. Researchers led by Professor Jean-Francois Perrier of the University of Copenhagen found that while serotonin helps to keep people going during the early stage of vigorous exercise, a build-up of the neurotransmitter in the brain can have the opposite effect by causing “central fatigue” of the nervous system even when the muscles are still able to carry on. “We can now see it is actually a surplus of serotonin that triggers a braking mechanism in the brain. In other words, serotonin functions as an accelerator but also as a brake when the strain becomes excessive,” said Professor Perrier, whose study is published in the Proceedings of the National Academy of Sciences. © independent.co.uk
Link ID: 17868 - Posted: 03.05.2013
By James Gallagher Health and science reporter, BBC News A run of poor sleep can have a dramatic effect on the internal workings of the human body, say UK researchers. The activity of hundreds of genes was altered when people's sleep was cut to less than six hours a day for a week. Writing in the journal Proceedings of the National Academy of Sciences, the researchers said the results helped explain how poor sleep damaged health. Heart disease, diabetes, obesity and poor brain function have all been linked to substandard sleep. What missing hours in bed actually does to alter health, however, is unknown. So researchers at the University of Surrey analysed the blood of 26 people after they had had plenty of sleep, up to 10 hours each night for a week, and compared the results with samples after a week of fewer than six hours a night. More than 700 genes were altered by the shift. Each contains the instructions for building a protein, so those that became more active produced more proteins - changing the chemistry of the body. Meanwhile the natural body clock was disturbed - some genes naturally wax and wane in activity through the day, but this effect was dulled by sleep deprivation. Prof Colin Smith, from the University of Surrey, told the BBC: "There was quite a dramatic change in activity in many different kinds of genes." Areas such as the immune system and how the body responds to damage and stress were affected. BBC © 2013
Link ID: 17848 - Posted: 02.26.2013
An international team of biologists has successfully identified some of the brain chemicals that may help clarify some unanswered questions about how humans sleep. The research - conducted by the University of California, Los Angeles (UCLA) and the University of Toronto - focused on seals and the chemicals found in their brain, as they are able to sleep with half their brain at a time. Professor John Peever of the University of Toronto said: "Seals do something biologically amazing - they sleep with half their brain at a time. The left side of their brain can sleep while the right side stays awake. Seals sleep this way while they're in water, but they sleep like humans while on land. Our research may explain how this unique biological phenomenon happens." The study's first author, PhD student Jennifer Lapierre, measured how the brain chemicals change while the seals are asleep and awake. She found that acetylcholine - an important brain chemical - was at low levels on the sleeping side of the brain, but high levels on the waking side. This discovery suggests that acetylcholine may be responsible for brain alertness. They also discovered - to their surprise - that the chemical serotonin was present in both sides of the brain whether the seal was awake or asleep. It was previously thought that serotonin caused brain arousal. Researchers hope that the discovery of the chemicals may make a breakthrough in understanding and curing sleeping disorders. The study's senior author, Jerome Siegel from UCLA's Brain Research Institute added: "Understanding which brain chemicals function to keep us awake or asleep is a major scientific advance. It could help solve the mystery of how and why we sleep." © independent.co.uk
Link ID: 17840 - Posted: 02.23.2013