Chapter 10. Biological Rhythms and Sleep
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By NICHOLAS BAKALAR Children who do not sleep enough may be increasing their risk for obesity, according to a new study. Researchers randomly divided 37 children aged 8 to 11 into two groups. Each group increased their habitual time in bed by an hour and a half per night for one week, then decreased their time by the same amount the next week. They wore electronic devices to measure sleep time, were assessed for daily food intake three times a week, and had blood tests to measure leptin, a hormone that affects hunger, and high levels of which correlate with fat tissue accumulations. Children consumed 134 calories fewer each day during the increased sleep week than the during the week with less sleep. Fasting leptin levels were lower when the children slept more and, over all, the children’s weight averaged about a half pound less at the end of long sleep weeks than short ones. The study was published online in Pediatrics. The lead author, Chantelle N. Hart, an associate professor of public health at Temple University who was at Brown University when she did the study, cautioned that it was small, and looked only at acute changes in sleep and their effect on eating behaviors. Still, she said, “I think these findings suggest that getting a good night’s sleep in childhood could have important benefits for weight regulation through decreased food intake.” Copyright 2013 The New York Times Company
By Joss Fong Sleep is such a large feature of our lives that it’s easy to forget how utterly weird it is. Every night, if we’re lucky, our brain cells switch into a synchronized pattern, putting our lives and minds on hold for hours. Sleep scientists have yet to fully explain why we spend a third of our lives in this state, let alone why we use some of that time wandering through vivid, nonsensical and sometimes upsetting hallucinations. A recent study in Science suggests that sleep may serve to wash the brain of harmful waste products that build up during the day. Medical researchers observed an increased flow of cerebrospinal fluid in mice that were sleeping or anesthetized. This fluid carries away waste proteins, including one linked to Alzheimer’s disease. The findings join other theories on the function of sleep, some of which I discuss above, in our latest Instant Egghead video. © 2013 Scientific American
Link ID: 18878 - Posted: 11.06.2013
by Simon Makin Sometimes wacky-sounding ideas aren't so crazy after all. If your body clock is all at sea after a long flight or a night shift, the way to reset it may be to scramble your timekeeping neurons even further. The body's master clock resides in a region of the brain called the suprachiasmatic nucleus. Each neuron in the SCN keeps its own time, but the neurons can synchronise their clocks by sending and receiving signals using a hormone called vasoactive intestinal polypeptide (VIP). When Erik Herzog at Washington University in St Louis, Missouri, and colleagues probed the hormone's effects, they discovered that a glut of VIP caused the neurons to lose the ability to synchronise. Herzog's team wondered whether this might have a beneficial effect. "If the cell rhythms are messed up and out of phase, the system may be more sensitive to environmental cues than it would be if all the cells were in sync," he says, allowing the body clock to adjust more readily. The VIP treatment To test the idea, they gave some mice an injection of VIP into the brain before fast-forwarding the light/dark cycle in their cages by 8 hours. The mice that received the hormone adjusted in 4.5 days on average, whereas untreated mice needed nearly eight days – gauging by how active the animals were when the lights were off. © Copyright Reed Business Information Ltd.
Keyword: Biological Rhythms
Link ID: 18855 - Posted: 10.30.2013
by Linda Geddes Anaesthetics usually knock you out like a light. But by slowing the process down so that it takes 45 minutes to become totally unresponsive, researchers have discovered a new signature for unconsciousness. The discovery could lead to more personalised methods for administering anaesthetics and cut the risks associated with being given too high or too low a dose. It also sheds new light on what happens to our brain when we go under the knife. Hundreds of thousands of people are anaesthetised every day, yet researchers still don't fully understand what's going on in the anaesthetised brain. Nor is there a direct way of measuring when someone is truly unresponsive. Instead, anaesthetists rely on indirect measures such as heart and breathing rate, and monitoring reflexes. To investigate further, Irene Tracey and her colleagues at Oxford University slowed the anaesthesia process down. Instead of injecting the anaesthetic propofol in one go, which triggers unconsciousness in seconds, the drug was administered gradually so that it took 45 minutes for 16 volunteers to become fully anaesthetised. Their brain activity was monitored throughout using electroencephalography (EEG). The study was then repeated on 12 of these volunteers using functional magnetic resonance imaging (fMRI). EEG recordings revealed that before the volunteers became completely unresponsive to external stimuli they progressed through a sleep-like state characterised by slow-wave oscillations – a hallmark of normal sleep, in which neurons cycle between activity and inactivity. As the dose of anaesthetic built up, more and more neurons fell into this pattern, until a plateau was reached when no more neurons were recruited, regardless of the dose administered. © Copyright Reed Business Information Ltd.
By Consumer Reports, You wake up tired after a full night’s sleep. Maybe you’ve become a bit forgetful, and you struggle to stay awake at work or behind the wheel. The problem might be obstructive sleep apnea, an often overlooked condition that has increased sharply in the past 20 years. In the United States, more than 40 percent of men and 28 percent of women between the ages of 50 and 70 experience obstructed breathing while asleep, according to researchers whose work was published online in April by the American Journal of Epidemiology. About 17 percent of the men and 9 percent of the women have cases serious enough to meet the Medicare criteria for a sleep apnea diagnosis. But even milder cases can affect your health. Obstructive sleep apnea causes the muscles and tissues in the lower throat to collapse, blocking the flow of air to the lungs during sleep. A person with obstructive sleep apnea may stop breathing, typically for 20 to 25 seconds or for as long as two minutes. The amount of carbon dioxide in the blood rises, triggering an alarm in the brain that stirs the sleeper to resume breathing. That cycle can repeat itself dozens of times an hour throughout the night, preventing the sleeper from reaching the restorative stages of deep sleep. Upon awakening, he or she usually has no recollection of those events. Overweight men are the most frequently affected because they tend to have a throat with bulkier soft tissue and fat deposits, but women and people of normal weight also develop sleep apnea. Loud snoring can be a warning sign, especially if you learn from a bed partner or roommate that you gasp for breath or choke while you are asleep. High blood pressure and heart-rhythm abnormalities are also red flags, especially if you take antihypertensive medication and still have trouble keeping blood pressure under control. Waking up with a headache may also signal the condition. © 1996-2013 The Washington Post
Link ID: 18820 - Posted: 10.22.2013
Maggie Fox NBC News Every cell in your body has a little clock ticking away in it, researchers reported on Sunday. And while most of you is aging in a coordinated way, odd anomalies that have the researchers curious: Your heart may be “younger” than the rest of your tissues, and a woman’s breasts are older. Tumors are the oldest of all, a finding reported in the journal Genome Biology that might help scientists better understand cancer, explain why breast cancer is so common and help researchers find better ways to prevent it. Less surprising, but intriguing: embryonic stem cells, the body’s master cells, look just like newborns with a biological age of zero. The new measurements might be useful in the search for drugs or other treatments that can turn back the clock on aging tissue and perhaps treating or preventing diseases of aging, such as heart disease and cancer, says Steve Horvath, a professor of genetics at the David Geffen School of Medicine at UCLA. “The big question is whether the biological clock controls a process that leads to aging,” Horvath said. Horvath looked at a genetic process called methylation. It’s a kind of chemical reaction that turns on or off stretches of DNA. All cells have the entire genetic map inside; methylation helps determine which bits of the map the cells use to perform specific functions.
Keyword: Biological Rhythms
Link ID: 18816 - Posted: 10.21.2013
By GRETCHEN REYNOLDS If you consider yourself to be a born morning person or an inveterate night owl, there is new research that supports your desire to wake up early or stay up late. Each of us has a personal “chronotype,” or unique circadian rhythm, says Till Roenneberg, a professor of chronobiology at Ludwig Maximilian University in Munich and one of the world’s experts on sleep. In broad strokes, these chronotypes are usually characterized as early, intermediate or late, corresponding to people who voluntarily go to bed and wake early, at a moderate hour or vampirishly late. If you are forced to wake up earlier than your body naturally would, you suffer from what Roenneberg calls “social jet lag.” People with an early chronotype may do well with a 7 a.m. workday rising time, but others do not. Sleeping out of sync with your innate preferences can be detrimental to your health, especially for late chronotypes, who tend to be the most at odds with typical work schedules. A study conducted by the National Institutes of Health and published in March in PLOS ONE found that obese adults with late chronotypes tended to eat larger meals, develop more sleep apnea and have higher levels of stress hormones and lower levels of HDL, or “good,” cholesterol than obese people with other chronotypes. Their chronotype may also have contributed to weight gain in the first place, Roenneberg says. Research has shown that a single hour of social jet lag, the mismatch between your chronotype and your schedule, increases your risk for obesity by about 33 percent. In a study published in June in Chronobiology International, late-night chronotypes gained more weight during their freshman years at college than other new students did, even though college is one of the best fits for night owls. Copyright 2013 The New York Times Company
by Tina Hesman Saey Sleep hoses garbage out of the brain, a study of mice finds. The trash, including pieces of proteins that cause Alzheimer’s disease, piles up while the rodents are awake. Sleep opens spigots that bathe the brain in fluids and wash away the potentially toxic buildup, researchers report in the Oct. 18 Science. The discovery may finally reveal why sleep seems mandatory for every animal. It may also shed new light on the causes of neurodegenerative disorders such as Alzheimer’s and Parkinson’s diseases. “It’s really an eye-opening and intriguing finding,” says Chiara Cirelli, a sleep researcher at the University of Wisconsin–Madison. The results have already led her and other sleep scientists to rethink some of their own findings. Although sleep requirements vary from individual to individual and across species, a complete lack of it is deadly. But no one knows why. One popular idea is that sleep severs weak connections between brain cells and strengthens more robust connections to solidify memories (SN Online: 4/2/09; SN Online: 6/23/11). But a good memory is not a biological imperative. “You don’t die from forgetting what you learned yesterday,” says Maiken Nedergaard, a neuroscientist at the University of Rochester Medical Center in New York who led the study. Researchers in Nedergaard’s lab stumbled upon sleep’s role in garbage clearance while studying a brain drainage system they described last year (SN: 9/22/12, p. 15). This service, called the glymphatic system, flushes fluid from the brain and spinal cord into the space between brain cells. Ultimately, the fluid and any debris it carries washes into the liver for disposal. © Society for Science & the Public 2000 - 2013
by Laura Sanders After Baby V joined our team, one of the first things people would ask is, “Are you getting any sleep?” (The answer was, and is, no.) The recurring question highlights how sorely lacking sleep is for new parents. Capitalism noticed us tired parents, too: Countless products beckon exhausted families with promises of eight, 10, even 12 hours of blissful, uninterrupted sleep. You can buy special swaddles, white noise machines, swings that sway like a moving car and books upon books that whisper contradictory secrets of how to get your baby to sleep through the night. (If you don’t have time to read them all, mother-of-twins Ava Neyer helpfully breaks down all of the advice for you.) As the owner of a stack of such books, I was intrigued by this recent review: “Behavioral sleep interventions in the first six months of life do not improve outcomes for mothers or infants: A systematic review.” Excuse me? The Sleep Sheep, the Baby Whisperer and the Sleep Lady lied to me? At the behest of the United Kingdom’s National Institute for Health Research, Australians Pamela Douglas and Peter Hill combed through the existing scientific literature on sleep interventions looking for benefits. These interventions included delaying responses to infant cues (also known by its cold-hearted name of “crying it out”), sticking to a feeding or sleeping schedule and other ways that aim to teach a baby how to fall asleep without the need to eat or be held. After analyzing 43 studies on infant sleep interventions, the team concluded that these methods weren’t beneficial for babies younger than six months, or their mothers. The studies didn’t convincingly show that interventions curb infant crying, prevent sleep or behavioral problems later or protect against maternal depression, Douglas and Hill write in the September Journal of Developmental & Behavioral Pediatrics. © Society for Science & the Public 2000 - 2013.
by Andy Coghlan Swifts are said to spend most of their lives airborne, but no one has ever proved this. Now, a study suggests there's some truth to it: alpine swifts spend more than six consecutive months aloft, not even resting after migrating to north Africa following their breeding season in Europe. "Up to now, such long-lasting locomotive activity had been reported only for animals living in the sea," says Felix Liechti of the Swiss Ornithological Institute in Sempach. Liechti and his colleagues attached 1.5-gram data loggers to three alpine swifts (Tachymarptis melba) at a Swiss breeding site, and recaptured the birds the following year. The loggers recorded the birds' acceleration and geographic location. The measurements suggest that for 200 days, all three swifts remained airborne while migrating to and wintering in Africa. Liechti says researchers have previously asserted but never proved that newborn common swifts spend three years aloft before landing for breeding. "Amazing, truly amazing," says Carsten Egevang of the Greenland Institute of Natural Resources in Nuuk of Liechti's findings. "We knew that swifts stay on the wing for long periods, but 200 days is very impressive." The birds survive on airborne plankton, and almost certainly sleep on the wing too, Liechti says. "It has been assumed that the birds 'sleep' only for seconds, or use only one half of the brain while the other half is resting," he says. © Copyright Reed Business Information Ltd
Link ID: 18767 - Posted: 10.09.2013
by Ed Yong I’ve just arrived home from 14 hours of flying. The clocks on my phone and laptop have been ticking away the whole time, and it takes a few seconds to reset them to British time. The clocks in my body are more difficult. We run on a daily 24-hour body clock, which controls everything from our blood pressure to our temperature to how hungry we feel. It runs on proteins rather than gears. Once they’re built, these proteins stop their own manufacture after a slight delay, meaning that their levels rise and fall with a regular rhythm. These timers tick away inside almost all of our cells, and they’re synchronised by a tiny collection of 10,000 neurons at the bottom of our brain. It’s called the suprachiasmatic nucleus (SCN). It’s the master clock. It’s the conductor that keeps the orchestra in sync. The SCN is also sensitive to light. It gets signals from our eyes, which allows it to synchronise its ticking with the 24-hour cycle of day and night outside. The SCN is what connects the rhythms of our bodies with those of the planet. But when we travel far and fast, and suddenly land in a new time zone, the SCN becomes misaligned with the environment. It takes time to re-adjust, typically one day for every time zone crossed. In the meantime, our sleep is disrupted and our physiology goes weird. In other words: jet lag. But at Kyoto University, Yoshiaki Yamaguchi and Toru Suzuki have engineered mice that break this rule. They are, with apologies for the awful word, unjetlaggable. If you change the light in their cages to mimic an 8-hour time difference, they readjust almost immediately. Put them on a red-eye flight from San Francisco to London and they’d be fine.
Answer by Paul King, computational neuroscientist: The emerging view in neuroscience is that dreams are related to memory consolidation happening in the brain during sleep. This may include reorganizing and recoding memories in relation to emotional drives as well as transferring memories between brain regions. During the day, episodic memories (memories for events) are stored in the hippocampus, a region of the brain specialized for long-term memory that learns particularly quickly. At night, memories from this region appear to be transferred to the cerebral cortex, the region specialized for information processing, cognition, and knowledge. Studies in animals have found that during sleep, the neural activity of the hippocampus "replays" the events of the day. This replay happens faster than real-time, and sometimes happens in reverse. The activity replay is correlated with neural activity patterns in both the visual cortex (responsible for visual experience) and the prefrontal cortex (responsible for strategy, goals, and planning). The memory replay occurs during REM sleep and dreaming. Philosopher Daniel Dennett proposes the Dream Weaving party game: One person, the Dream Guesser is asked to leave the room, and while away, someone will share a dream with the group. When the Dream Guesser returns, their job will be to ask yes/no questions of random people in the group to attempt to reconstruct the plot of the dream. © 2013 The Slate Group, LLC.
Link ID: 18744 - Posted: 10.05.2013
by Linda Geddes They say the early bird catches the worm, but night owls may be missing far more than just a tasty snack. Researchers have discovered the first physical evidence of structural brain differences that distinguish early risers from people who like to stay up late. The differences might help to explain why night owls seem to be at greater risk of depression. Around 10 per cent of people qualify as morning people or larks, and a further 20 per cent are night owls – with the rest of us falling somewhere in between. Your lark or night owl status is called your chronotype. Previous studies have suggested that night owls experience worse sleep, more tiredness during the day and consume greater amounts of tobacco and alcohol. This has prompted some to suggest that they are suffering from a form of chronic jet lag. To investigate further, Jessica Rosenberg at RWTH Aachen University in Germany and colleagues used diffusion tensor imaging to scan the brains of 16 larks, 23 night owls and 20 intermediate chronotypes. They found a reduction in the integrity of night owls' white matter – brain tissue largely comprised of fatty insulating material that speeds up the transmission of nerve signals – in areas associated with depression. "We think this could be caused by the fact that late chronotypes suffer from this permanent jet lag," says Rosenberg, although she cautions that further studies are needed to confirm cause and effect. © Copyright Reed Business Information Ltd.
By Tina Hesman Saey The sun exerts hegemony over biological rhythms of nearly every organism on Earth. But two studies now show the moon is no slouch. It controls the cadence of at least two different biological clocks: one set by tides and the other by moonlight. The clocks, both discovered in sea creatures, work independently of the circadian clock, which synchronizes daily rhythms with the sun. The studies demonstrate that the moon’s light and its gravitational pull, which creates tides, can affect the behavior of animals. “The moon has an influence, definitely,” says Steven Reppert, a neurobiologist at the University of Massachusetts Medical School in Worcester, who was not involved with either study. “Clearly for these marine organisms, it’s very powerful and important.” Scientists established decades ago that circadian clocks govern people’s daily cycles of such things as hormone levels, blood pressure and body temperature. Nearly every organism, including single-celled creatures, has some version. Circadian clocks are composed of protein gears. In a loop that takes roughly 24 hours, levels of some proteins rise and then fall, while others fall and then rise. Sunlight sets the clocks, but once a clock is set it will keep running, even when scientists keep organisms in constant darkness. © Society for Science & the Public 2000 - 2013
Keyword: Biological Rhythms
Link ID: 18714 - Posted: 09.28.2013
Few features of child-rearing occupy as much parental brain space as sleep, and with it the timeless question: Is my child getting enough? Despite the craving among many parents for more sleep in their offspring (and, by extension, themselves), the purpose that sleep serves in young kids remains something of a mystery—especially when it comes to daytime naps. Do they help children retain information, as overnight sleep has been found to do in adults? A study published today in the Proceedings of the National Academy of Sciences provides the first evidence that daytime sleep is critical for effective learning in young children. Psychologist Rebecca Spencer of the University of Massachusetts (UMass), Amherst, had more than a passing interest in the subject: Her daughters were 3 and 5 when she began chasing answers to these questions. She also wondered about growing enthusiasm for universal public preschool, where teachers don’t necessarily place much emphasis on naps. “There is a lot of science” about the best curriculum for preschool classrooms, “but nothing to protect the nap,” Spencer says. Still, data to support a nap’s usefulness were scarce: Studies in adults have found that sleep helps consolidate memories and learning, but whether the same is true of brief naps in the preschool set was unknown. So Spencer approached the first preschool she could think of that might help her find out: her daughters’. She later added other local preschools to her sample, for a total of 40 children ranging from nearly 3 to less than 6 years old. The goal of Spencer, her graduate student Laura Kurdziel, and undergraduate Kasey Duclos of Commonwealth Honors College at UMass, was to compare each child against him or herself: How well did a child learn when she napped, and what happened when she didn’t? © 2012 American Association for the Advancement of Science
By Laura Sanders A nap can ease the burden of a painful memory. While fast asleep, people learned that a previously scary situation was no longer threatening, scientists report September 22 in Nature Neuroscience. The results are the latest to show that sleep is a special state in which many sorts of learning can happen. And the particular sort of learning in the new study blunted a fear memory, a goal of treatments for disorders such as phobias and post-traumatic stress disorder. “It’s a remarkable finding,” says sleep neuroscientist Edward Pace-Schott of Harvard Medical School and Massachusetts General Hospital. Researchers led by Katherina Hauner of Northwestern University’s Feinberg School of Medicine first taught 15 (awake) volunteers to fear the combination of a face and odor. Participants saw a picture of a certain man’s face and at the same time smelled a distinctive scent, such as lemon. This face-odor combo was paired with a nasty shock, so that the volunteers quickly learned to expect something bad when they saw that particular face and smelled the associated odor. Then the volunteers tucked in for a nap in the laboratory. When the participants hit the deepest stage of sleep, called slow-wave sleep, Hauner and her colleagues redelivered the smell that had earlier come with a shock. During the nap, some participants had learned that the smell was safe. The volunteers sweated less (a measure of fear) when the face-odor combination appeared after the nap, the scientists found. When the odor wasn’t presented during sleep, volunteers’ responses to the associated face were unchanged. © Society for Science & the Public 2000 - 2013
By Melissa Healy It's a question that has long fascinated and flummoxed those who study human behavior: From whence comes the impulse to dream? Are dreams generated from the brain's "top" -- the high-flying cortical structures that allow us to reason, perceive, act and remember? Or do they come from the brain's "bottom" -- the unheralded brainstem, which quietly oversees such basic bodily functions as respiration, heart rate, salivation and temperature control? At stake is what to make of the funny, sexual, scary and just plain bizarre mental scenarios that play themselves out in our heads while we sleep. Are our subconsious fantasies coming up for a breath of air, as Sigmund Freud believed? Is our brain consolidating lessons learned and pitching out unneeded data, as neuroscientists suggest? Or are dreams no more meaningful than a spontaneous run of erratic heartbeats, a hot flash, or the frisson we feel at the sight of an attractive passer-by? A study published this week in the journal Brain suggests that the impulse to dream may be little more than a tickle sent up from the brainstem to the brain's sensory cortex. The full dream experience -- the complex scenarios, the feelings of fear, delight or longing -- may require the further input of the brain's higher-order cortical areas, the new research suggests. But even people with grievous injury to the brain's prime motivational machinery are capable of dreams, the study found.
Link ID: 18642 - Posted: 09.14.2013
Scientists believe they have discovered a new reason why we need to sleep - it replenishes a type of brain cell. Sleep ramps up the production of cells that go on to make an insulating material known as myelin which protects our brain's circuitry. The findings, so far in mice, could lead to insights about sleep's role in brain repair and growth as well as the disease MS, says the Wisconsin team. The work is in the Journal of Neuroscience. Dr Chiara Cirelli and colleagues from the University of Wisconsin found that the production rate of the myelin making cells, immature oligodendrocytes, doubled as mice slept. The increase was most marked during the type of sleep that is associated with dreaming - REM or rapid eye movement sleep - and was driven by genes. In contrast, the genes involved in cell death and stress responses were turned on when the mice were forced to stay awake. Precisely why we need to sleep has baffled scientists for centuries. It's obvious that we need to sleep to feel rested and for our mind to function well - but the biological processes that go on as we slumber have only started to be uncovered relatively recently. Dr Cirelli said: "For a long time, sleep researchers focused on how the activity of nerve cells differs when animals are awake versus when they are asleep. "Now it is clear that the way other supporting cells in the nervous system operate also changes significantly depending on whether the animal is asleep or awake." The researchers say their findings suggest that sleep loss might aggravate some symptoms of multiple sclerosis (MS), a disease that damages myelin. BBC © 2013
Charlie Cooper Scientists have moved a step closer to creating a specialist pill for jet lag, after research in mice revealed a possible mechanism for speeding up the body's natural response to moving across time zones. Researchers at the University of Oxford found they could improve the recovery time of mice exposed to irregular patterns of light and dark by blocking a particular gene in the brain, responsible for regulating the body's internal clock. Nearly all living things have an internal, subcellular mechanism - known as the circadian clock - that synchronises a variety of bodily functions to the 24-hour rhythm of the Earth's rotation. The circadian clock is regulated by a number of stimuli - chief among them light detected by the eye. But when daily patterns of light and dark are disrupted - as when we travel across several time-zones - the body clock falls out of synch, resulting in several days of fatigue and discomfort as our cells adjust to new daily patterns - experienced by long-haul fliers as jet lag. The body takes about one day to adjust for every time zone crossed. To understand the effect this has on the brain, researchers at the University of Oxford exposed mice to irregular patterns of light and dark to simulate moving across time zones. They monitored the activity of genes in the part of the brain responsible for setting the circadian clock - the suprachiasmatic nuclei (SCN) and observed that hundreds of genes were activated by light detected from the eye, all of which helped the body adjust to a new day-night rhythm. © independent.co.uk
Keyword: Biological Rhythms
Link ID: 18590 - Posted: 08.31.2013
Brain scans of people who say they have insomnia have shown differences in brain function compared with people who get a full night's sleep. Researchers at the University of California, San Diego, said the poor sleepers struggled to focus part of their brain in memory tests. Other experts said that the brain's wiring may actually be affecting perceptions of sleep quality. The findings were published in the journal Sleep. People with insomnia struggle to sleep at night, but it also has consequences during the day such as delayed reaction times and memory. The study compared 25 people who said they had insomnia with 25 who described themselves as good sleepers. MRI brain scans were carried out while they performed increasingly challenging memory tests. One of the researchers, Prof Sean Drummond, said: "We found that insomnia subjects did not properly turn on brain regions critical to a working memory task and did not turn off 'mind-wandering' brain regions irrelevant to the task. "This data helps us understand that people with insomnia not only have trouble sleeping at night, but their brains are not functioning as efficiently during the day." BBC © 2013