Chapter 14. Biological Rhythms, Sleep, and Dreaming

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By Jade Wu Savvy Psychologist This week, let’s ask the million-dollar question: How much sleep do you really need? We all know sleep is important. Shakespeare called it the “sore labor’s bath, balm of hurt minds, great nature’s second course, chief nourisher in life’s feast.” Less poetically, headlines these days seem to be shouting: “Sleep deprivation will make you slower and dumber!” “It will give you Alzheimer's disease and heart attacks!” One mattress advertisement I saw simply said, “You can only live seven days without sleep.” Yikes. Talk about pressure to perform! Fear-mongering aside, there is good evidence that sleep is important for health, well-being, and performance. A recent meta-analysis including over 1600 participants confirmed that sleep restriction is associated with poorer attention and thinking. We’ve known for decades that sleep deprivation disrupts mood. For example, it can trigger manic episodes in those with bipolar disorder. And we’re learning now, from researchers in Sweden and Germany, that insufficient sleep can even affect the microbiota in your gut. But how much sleep is enough? Is there such a thing as too much sleep? If you ask Dr. Google, you’ll get over a billion answers. (That’s right; “billion” with a “b.”) The most common answer seems to be “eight hours.” That seems pretty straightforward. But where does this number come from? And if you’re thinking, “Dr. Google hasn’t examined me; how would she know how much sleep I need,” then you’re asking exactly the right question. © 2020 Scientific American

Keyword: Sleep
Link ID: 26977 - Posted: 01.22.2020

By Harry Guinness The world isn’t made for night owls. You struggle into work in the dark hours before 10 a.m. — or your morning coffee — and you’re greeted by some chipper person who has already been to the gym and is six items into his to-do list. I used to fantasize about fitting punishments for such morning people, but in the last two years I’ve seen the (morning) light, and I’ve become one of them. If you love staying up late but hate crawling through your mornings in a haze, here’s how you can do it too. After a long, draining day you finally get home, settle down in front of the TV and throw on whatever season you’re currently bingeing. Heaven. But then, when a reasonable bedtime rolls around, you don’t want to stop. It has been a hard day, aren’t you entitled to just one more episode? So you push play, trade a bit of sleep for more Netflix time and continue the cycle that keeps you tired all the time. Dr. Alex Dimitriu, founder of the Menlo Park Psychiatry and Sleep Medicine clinic, explained it like this: “Long days leave us tired and exhausted, but the reality is, our days would be less hard, and less exhausting, if we weren’t so tired through them. The trouble with being a night owl is that your sleep gets clipped in the morning hours, where most of the precious REM or dream sleep occurs. Instead of sleeping seven or eight hours per night, most night owls get forced to sleep five or six — with a hard start time in the morning.” Dr. Dimitriu can’t stress enough just how important REM sleep is. It’s “the key to our emotional and creative energy” and comparable to “self-therapy,” he said, adding that it “balances us out in more ways than I can describe” and that without enough of it, our memory and moods take a hit. If you have the freedom to wake up when you like, then things are different, but if that extra Netflix episode is forcing you to cut your sleep short, then you should try to do something about it. © 2020 The New York Times Company

Keyword: Biological Rhythms; Sleep
Link ID: 26973 - Posted: 01.21.2020

By Tom Siegfried Long before Apple watches, grandfather clocks or even sundials, nature provided living things with a way to tell time. Life evolved on a rotating world that delivered alternating light and darkness on a 24-hour cycle. Over time, cellular chemistry tuned itself to that rhythm. Today, circadian rhythms — governed by a master timekeeper in the brain — guide sleeping schedules and mealtimes and influence everything from diet to depression to the risk of cancer. While an Apple watch can monitor a few vital functions such as your heart rate, your body’s natural clock controls or affects nearly all of them. Lately, research by Takahashi and others has suggested strategies for manipulating the body’s clock to correct circadian-controlled chemistry when it goes awry. Such circadian interventions could lead to relief for shift workers, antidotes for jet lag, and novel treatments for mood disorders and obesity, not to mention the prospect of counteracting aging. Prime weapons for the assault on clock-related maladies, Takahashi believes, can be recruited from an arsenal of small molecules, including some existing medical drugs. “Researchers are increasingly interested in developing small molecules to target the circadian system directly for therapeutic gains,” Takahashi and coauthors Zheng Chen and Seung-Hee Yoo wrote in the 2018 Annual Review of Pharmacology and Toxicology. In sophisticated life-forms (such as mammals), central control of the body’s clock resides in a small cluster of nerve cells within the brain’s hypothalamus. That cluster, called the suprachiasmatic nucleus — SCN for short — is tuned to the day-night signal by light transmitted via the eyes and the optic nerve. But the SCN does not do the job alone. It’s the master clock, for sure, but satellite timekeepers operate in all kinds of cells and body tissues. © 2020 Annual Reviews, Inc

Keyword: Biological Rhythms
Link ID: 26962 - Posted: 01.15.2020

By Philippa Roxby Health reporter A sleep disorder that can leave people gasping for breath at night could be linked to the amount of fat on their tongues, a study suggests. When sleep apnoea patients lost weight, it was the reduction in tongue fat that lay behind the resulting improvements, researchers said. Larger and fattier tongues are more common among obese patients. But the Pennsylvania team said other people with fatty tongues may also be at risk of the sleep disorder. The researchers now plan to work out which low-fat diets are particularly good at slimming down the tongue. Tongue tied "You talk, eat and breathe with your tongue - so why is fat deposited there?" said study author Dr Richard Schwab, of Perelman School of Medicine, Philadelphia. "It's not clear why - it could be genetic or environmental - but the less fat there is, the less likely the tongue is to collapse during sleep." Sleep apnoea is a common disorder that can cause loud snoring, noisy breathing and jerky movements when asleep. It can also cause sleepiness during the day, which can affect quality of life. The most common type is obstructive sleep apnoea, in which the upper airway gets partly or completely blocked during sleep. Those who are overweight or who have a large neck or tonsils are more likely to have the condition. Researchers at the Perelman School of Medicine, University of Pennsylvania, scanned 67 people with obstructive sleep apnoea who were obese and had lost 10% of their body weight, improving their symptoms improved by 30%. © 2020 BBC.

Keyword: Sleep; Obesity
Link ID: 26946 - Posted: 01.10.2020

By Matthew Hutson When you are stuck on a problem, sometimes it is best to stop thinking about it—consciously, anyway. Research has shown that taking a break or a nap can help the brain create pathways to a solution. Now a new study expands on the effect of this so-called incubation by using sound cues to focus the sleeping mind on a targeted problem. When humans sleep, parts of the brain replay certain memories, strengthening and transforming them. About a decade ago researchers developed a technique, called targeted memory reactivation (TMR), aimed at further reinforcing selected memories: when a sound becomes associated with a memory and is later played during sleep, that memory gets reactivated. In a study published last November in Psychological Science, scientists tested whether revisiting the memory of a puzzle during sleep might also improve problem-solving. About 60 participants visited the laboratory before and after a night of sleep. In an evening session, they attempted spatial, verbal and conceptual puzzles, with a distinct music clip repeating in the background for each, until they had worked on six puzzles they could not solve. Overnight they wore electrodes to detect slow-wave sleep—slumber's deepest phase, which may be important for memory consolidation—and a device played the sounds assigned to three of the six unsolved puzzles. The next day, back at the lab, the participants attempted the six puzzles again. (Each repeated the experiment with a different set of puzzles the following night.) All told, the subjects solved 32 percent of the sound-prompted puzzles versus 21 percent of the untargeted puzzles—a boost of more than 50 percent. © 2020 Scientific American

Keyword: Sleep; Learning & Memory
Link ID: 26938 - Posted: 01.07.2020

Getting a Good Night’s Sleep Without Drugs By Jane E. Brody As many as 20 percent to 30 percent of people in the general population sleep poorly. They may have difficulty falling asleep or staying asleep, some awaken much too early, while others do not feel rested despite spending a full night seemingly asleep in bed. For one person in 10, insomnia is a chronic problem that repeats itself night after night. Little wonder that so many resort to sleeping pills to cope with it. But experts report that there are better, safer and more long-lasting alternatives than prescription drugs to treat this common problem. The alternatives are especially valuable for older people who metabolize drugs more slowly, are more likely to have treatable underlying causes of their insomnia and are more susceptible to adverse side effects of medications. Is Your Sleep Cycle Out of Sync? It May Be Genetic By Jane E. Brody Early to bed, early to rise — a fine plan for a dairy farmer who has to get up long before dawn to milk the cows. But if you’re someone who works all day with stocks and clients and may want to enjoy an evening out now and then, it would be better not to be getting up at 2 a.m. and have to struggle to stay awake through dinner or a show. Such is the challenge faced by a friend who has what sleep specialists call an advanced sleep phase. Her biological sleep-wake cycle, or circadian rhythm, is out of sync with the demands of the modern world. Read more>>> By Perri Klass, M.D. The biology of adolescent sleep reflects a natural and normal delay in melatonin secretion that leads to a later sleep onset time, which unfortunately coincides with early high school start times, creating a high-stress set up. Pediatricians often see adolescents with insomnia, who have trouble falling asleep or staying asleep, waking up too early or finding sleep not restful or refreshing. © 2019 The New York Times Company

Keyword: Sleep
Link ID: 26919 - Posted: 12.27.2019

Alejandra Manjarrez When he was a postdoc at KU Leuven in Belgium, Daniel Vigo helped analyze results from an experiment that simulated a spaceflight to Mars. Six crew members were secluded in an artificially lit, spacecraft-like facility for 520 days starting in June 2010. Part of an international project known as the Mars500 mission, the experiment aimed to assess the psychological, social, and biological effects of prolonged confinement and isolation, along with the absence of normal day and night rhythms. That isolation, of course, was just an illusion, manufactured by the Institute for Biomedical Problems of the Russian Academy of Sciences and the European Space Agency. The simulation took place in central Moscow, where any sudden medical problems could have received immediate attention—as Vigo, now a researcher at the Catholic University of Argentina and a member of the National Scientific and Technical Research Council (CONICET), tells The Scientist in Spanish. He began wondering what would happen in a less artificial scenario. One of the key findings from the study, for example, was that confinement—in this case in an artificially lit building—disrupted normal sleep patterns: the crew members in the Mars500 experiment had suffered from sleep problems and rapidly fell into sleep-wake routines that were out of sync with one another. But what would the story be like for people experiencing a similarly extreme living environment, Vigo wondered, without the safety net provided by a carefully controlled simulation? © 1986–2019 The Scientist

Keyword: Sleep; Biological Rhythms
Link ID: 26918 - Posted: 12.27.2019

By Nicholas Bakalar The right diet might help you sleep better. In a study of 77,860 postmenopausal women, researchers found that consuming foods that had a low glycemic index is associated with a reduced risk for insomnia. Foods with low glycemic indexes — for example, vegetables, nuts and whole grain breads — have carbohydrates that are slowly absorbed and cause lower, and slower, rises in blood glucose and insulin levels after being consumed. For this study, in the American Journal of Clinical Nutrition, participants completed lengthy questionnaires about what foods they ate and how often. They also reported their degree of insomnia at the start of the study and after three years of follow-up. Compared with the one-fifth of participants whose diet had the lowest glycemic index, those with the highest were 11 percent more likely to have insomnia. Some low-glycemic index foods — whole grains and dairy foods, for example — were not associated with reduced insomnia. But people who ate the most fruits and vegetables were about 14 percent less likely to have insomnia, and the largest consumers of fiber were 13 percent less likely. In contrast, women who ate the most refined grains had a 16 percent higher risk of insomnia than those who ate the least. Although the study controlled for many health and behavioral characteristics, the study showed only an association and could not prove cause and effect. “Randomized controlled trials examining dietary patterns in relation to insomnia are needed to clarify these findings,” the authors write. © 2019 The New York Times Company

Keyword: Sleep; Obesity
Link ID: 26917 - Posted: 12.27.2019

By Elizabeth Pennisi Over 20 years, citizen scientists across North America tagged more than 1 million monarch butterflies as they flitted their way southward on one of nature’s more mysterious migrations. Now, scientists analyzing data from those journeys have discovered what may trigger them: the angle of the high noon Sun—which changes over time and as one moves closer to the equator. That “critical environmental factor” also seems to help monarchs time their daily travels and the end of their fall migration, says Steven Reppert, a neurobiologist at the University of Massachusetts Medical School in Worcester who studies monarch migrations, but was not involved with this work. As a result, adds University of California, Berkeley, evolutionary biologist Noah Whiteman, “a marvel of the natural world is a little closer to being understood.” The annual migration of monarchs (Danaus plexippus) from across the United States and eastern Canada to one small region of southwestern Mexico has long defied understanding. Ten years ago, lab and field studies showed that these butterflies have an internal clock in their antennae that helps them navigate based on the horizontal movements of the Sun. But no one knew what the trigger for their trek was—or how they paced their daily journeys. To learn more, a nonprofit organization called Monarch Watch began to distribute pinkie nail–size adhesive tags to thousands of volunteers, who put them on monarchs flying through their area and recorded the dates and locations of each tagging. From 1998 to 2015, more than 1.38 million butterflies were tagged, says Orley Taylor, an insect ecologist at the University of Kansas in Lawrence who started the program in 1992. After the butterflies arrived at their destination in southwestern Mexico, volunteers there searched for the tags. Altogether, they gathered more than 13,000. © 2019 American Association for the Advancement of Science.

Keyword: Animal Migration; Biological Rhythms
Link ID: 26903 - Posted: 12.19.2019

By Nicholas Bakalar Sleeping a lot may increase the risk for stroke, a new study has found. Chinese researchers followed 31,750 men and women whose average age was 62 for an average of six years, using physical examinations and self-reported data on sleep. They found that compared with sleeping (or being in bed trying to sleep) seven to eight hours a night, sleeping nine or more hours increased the relative risk for stroke by 23 percent. Sleeping less than six hours a night had no effect on stroke incidence. The study, in Neurology, also found that midday napping for more than 90 minutes a day was associated with a 25 percent increased risk for stroke compared with napping 30 minutes or less. And people who both slept more than nine hours and napped more than 90 minutes were 85 percent more likely to have a stroke. The study controlled for smoking, drinking, exercise, family history of stroke, body mass index and other health and behavioral characteristics. The reason for the association is unclear, but long sleep duration is associated with increased inflammation, unfavorable lipid profiles and increased waist circumference, factors known to increase cardiovascular risk. © 2019 The New York Times Company

Keyword: Stroke; Sleep
Link ID: 26890 - Posted: 12.12.2019

By Aaron E. Carroll and Austin Frakt Both of us have sleep apnea, and both of us receive treatment that makes a world of difference. It could make a big difference in your life, too. Sleep apnea is quite common, with estimates that it affects up to 17 percent of men 50 to 70, and 10 percent of men 30 to 49. But there’s a problem. In the American health system, we often make it hard for people to get care, and the same is true here. Obstructive sleep apnea is when the upper airway collapses during sleep, leading to periods of, well, not breathing. About 24 million Americans have sleep apnea and don’t know it, research suggests, and many who do know don’t get treatment. The consequences can be severe. It’s a leading cause of vehicle accidents, as apnea-afflicted drivers fall asleep behind the wheel. Snoring and sleep apnea are on the same spectrum and are associated with Type 2 diabetes in adults. Treatment is associated with improvements in insulin resistance. Having sleep apnea, and not treating it, increases the risk of postoperative cardiovascular surgery complications. Treating sleep apnea improves sleep duration and quality. People who sleep better are much happier and healthier in general. Reducing snoring also helps partners sleep better. How hard is it to get used to a mask? We were treated with continuous positive airway pressure (CPAP). It’s intrusive, though not nearly as much as we had feared. Each night we strap on masks connected to CPAP machines. The modern machines are silent. And we both use masks that cover only our nostrils, though others need full face masks. The air that the machines push through the masks keeps our airways open. It takes some getting used to, but we adapted within a week. This isn’t to say that it’s not a big deal for many people — it can be. But it’s not as scary as many fear. © 2019 The New York Times Company

Keyword: Sleep
Link ID: 26882 - Posted: 12.09.2019

By Aimee Cunningham Socially isolated and faced with a persistently white polar landscape, a long-term crew of an Antarctic research station saw a portion of their brains shrink during their stay, a small study finds. “It’s very exciting to see the white desert at the beginning,” says physiologist Alexander Stahn, who began the research while at Charité-Universitätsmedizin Berlin. “But then it’s always the same.” The crew of eight scientists and researchers and a cook lived and worked at the German research station Neumayer III for 14 months. Although joined by other scientists during the summer, the crew alone endured the long darkness of the polar winter, when temperatures can plummet as low as –50° Celsius and evacuation is impossible. That social isolation and monotonous environment is the closest thing on Earth to what a space explorer on a long mission may experience, says Stahn, who is interested in researching what effect such travel would have on the brain. Animal studies have revealed that similar conditions can harm the hippocampus, a brain area crucial for memory and navigation (SN: 11/6/18). For example, rats are better at learning when the animals are housed with companions or in an enriched environment than when alone or in a bare cage, Stahn says. But whether this is true for a person’s brain is unknown. Stahn, now at the Perelman School of Medicine at the University of Pennsylvania, and his colleagues used magnetic resonance imaging to capture views of the team members’ brains before their polar stay and after their return. On average, an area of the hippocampus in the crew’s brains shrank by 7 percent over the course of the expedition, compared with healthy people matched for age and gender who didn’t stay at the station, the researchers report online December 4 in the New England Journal of Medicine. © Society for Science & the Public 2000–2019

Keyword: Learning & Memory; Biological Rhythms
Link ID: 26874 - Posted: 12.05.2019

By Joanne Chen I grew up in New England, so you’d think I’d be used to winter by now. But after wearing dozens of puffy coats thin over my lifetime, that’s not the case: I hate the relentless chill, the heavy boots, the darkness. It’s enough to make anyone want to curl up under a blanket and snooze until March. But as Wirecutter’s sleep writer, I also know that many sleep-promoting products don’t actually do much. Winter tiredness is as mental as it is physical, and you need to consider things both in and out of the bedroom to reawaken your fun-loving self. To help make your seven to eight hours of sleep feel exactly that, here are four expert-approved strategies. Shorter days are largely to blame for the blahs. Light controls our circadian rhythm. Its presence suppresses the flow of the sleep hormone melatonin; its absence encourages it. When sunlight takes its own sweet time to arrive in the morning and slinks away before dinner, that sleepy feeling prevails, even if we’ve just slept. To mimic the refreshing effects of a bright spring morning — but in the darkness of 6 a.m. in winter — a sunrise alarm clock might help. We recommend the Philips Wake-Up Light HF3520. Its light gradually fills the room and peaks at the designated time. There’s a backup alarm too, which I set to the sound of birds chirping so I can pretend it’s actually May. A more integrated strategy: Outfit your home with smart bulbs instead, which you can program to brighten just as you would a sunrise alarm clock. If the thought of entering a dark home after work makes you want to ditch all household obligations, you can also arrange lights to turn on before you walk through your door. Philips Hue, Wirecutter’s smart-bulb pick, offers lighting “formulas” such as brighter intensities in the morning and warmer glows in the evening. (While you’re at it, why not program your smart speaker to play whatever song fires you up?) For an extra kick, light therapy lamps — like our pick, the Carex Day-Light Classic Plus Lamp — might help. Doctors often recommend these for seasonal affective disorder (S.A.D.), a type of depression triggered by certain seasons. (Talk to yours about whether the device is appropriate for you and how best to use it.) © 2019 The New York Times Company

Keyword: Biological Rhythms; Sleep
Link ID: 26852 - Posted: 11.26.2019

Alejandra Manjarrez Typically, the worm Caenorhabditis elegans falls asleep after it experiences stress or hours of swimming. In a recent study, scientists observed another sleep trigger: being confined to a microfluidic chamber. As such devices are widely used to analyze different worm behaviors, the authors caution that the sleep induction could interfere with data interpretation. The results were published November 6 in Nature Communications. “In our field, microfluidic chambers have become very commonly used, and they are valuable tools for precise environmental control and for neural imaging . . . but what this study highlights is that we are significantly impacting the physiology and behavior of these animals by confining them in such a way,” says Cheryl Van Buskirk, a geneticist at California State University in Northridge. Van Buskirk studies sleep and stress response in worms, but she was not involved in this research. The team first observed this behavior while developing a technique to make electrical measurements of individual cells in worms placed in microfluidic chambers. They noticed that the muscle cells of these animals would not show any activity during some periods of time. Inactivity, however, is not always equivalent to sleep. “There are specific criteria for sleep, so we actually spent a good deal of the [latest] paper testing those specific criteria,” says Daniel Gonzales, who participated in this study as a graduate student at Rice University in Houston, but has now moved to Purdue University in Indiana. They tested, for example, whether this behavior was reversible, if it was associated with a decreased response to stimuli, and if the worms took on a stereotypical sleep posture. They found that, in addition to fulfilling these criteria, this microfluidics-induced quiescence was also regulated by neurons previously reported to control sleep in C. elegans. © 1986–2019 The Scientist.

Keyword: Sleep
Link ID: 26840 - Posted: 11.21.2019

By Kim Tingley We humans spend a third of our lives asleep, oblivious to our surroundings and temporarily paralyzed. It’s a vulnerability that would seem to diminish our odds of survival, so evolutionarily speaking it must also somehow confer tremendous benefits. Yet our best guesses about what those benefits are tend to come from observing what happens when sleep is curtailed. As far as we know, all animals sleep in some way; deprive most of them of it for long enough, and they will die, but exactly why is unclear. In 2015, the American Academy of Sleep Medicine and the Sleep Research Society published a joint statement, based on a comprehensive review of research, saying that “sleeping less than seven hours per night on a regular basis” — which is the case for an estimated 35 to 40 percent of Americans during the workweek — is associated with adverse health outcomes. These include weight gain and obesity, diabetes, hypertension, heart disease and stroke, depression, impaired immune function, increased pain, greater likelihood of accidents and “increased risk of death.” The National Institutes of Health reported last year that sleep deficits may increase the beta-amyloid proteins in the brain linked with Alzheimer’s disease. But when it comes to “what sleep is, how much you need and what it’s for,” says Louis Ptacek, a professor of neurology at the University of California, San Francisco, “we know almost nothing — other than it’s bad not to get enough of it.” Indeed, says David Dinges, one of the statement’s authors and a professor of psychiatry at the University of Pennsylvania, “All of this makes it really tough to send out simple messages to the public about when you should sleep and how much you should sleep.” Scientists believe that there are two separate but interrelated internal systems that regulate sleep. The first is the circadian system that tells our body when to sleep. Medicine already knows a great deal about how it works: Approximately every 24 hours, the suprachiasmatic nucleus, a small region in the hypothalamus, orchestrates physiological changes to prepare us for sleep, like lowering body temperature and releasing dopamine. But the second system — the one that tells our body the amount of sleep it needs — is still mysterious. One way to elucidate it would be to find genes that govern how long or deeply people sleep and observe where those genes are active. This fall, Ptacek, Ying-Hui Fu and other colleagues announced, in the journals Neuron and Science Translational Medicine, the discovery of two genetic mutations that seem to cause certain people to sleep far less than average. This brought the number of genes known to be involved in sleep duration to just three. © 2019 The New York Times Company

Keyword: Sleep
Link ID: 26833 - Posted: 11.19.2019

By Nicholas Bakalar Poor sleepers may be at increased risk for cardiovascular disease. Chinese researchers used data on 487,200 people ages 30 to 79, generally healthy at the start of the study. The participants reported on the frequency of three symptoms of poor sleep: difficulty falling or staying asleep, daytime sleepiness and early morning awakening. The study is in Neurology. The scientists followed the group for an average of 10 years, during which there were 130,032 cases of cardiovascular disease. After adjusting for age, alcohol consumption, family history of cardiovascular disease and many other factors, they found that difficulty falling asleep was associated with a 9 percent increased relative risk for cardiovascular disease, early morning awakening with a 7 percent increased risk, and daytime sleepiness with a 13 percent increased risk. Compared with those who had no sleep problems, those with all three symptoms had an 18 percent increased relative risk of cardiovascular disease. The link was especially strong in younger people. The lead author, Canqing Yu, an associate professor at Peking University, noted that the sleep data depended on self-reports, and this observational study does not prove cause and effect. “People with difficulty sleeping shouldn’t be alarmed by this finding,” he said. “Poor sleep is a minor contributor to cardiovascular disease. But among young people who have no other risk factors, this can be important.” © 2019 The New York Times Company

Keyword: Sleep
Link ID: 26813 - Posted: 11.12.2019

By Austin Frakt Daylight Saving Time ended on Sunday, and for many of us the extra hour of sleep has provided a small energy boost. It’s widely known that sleep affects our mood and health. Less understood is how it can also affect our paychecks. A study published last year in the Review of Economics and Statistics found that workers who live in locations where people get more sleep tend to earn more than those in areas where people get less. One theory: Better-rested workers are more productive and are compensated for it with additional income. “There are other explanations, but we consider them less likely,” said an author of the study, Matthew Gibson, an economist at Williams College. It’s not as if simply sleeping more will cause your boss to pay you more. In fact, if you get that extra sleep by being late for work, you might earn less or even lose your job. So how would the sleep-income relationship actually work? Studying the issue is complicated by reverse causality: Not only does sleep affect work, but work also affects sleep. On an individual level, people who work more, and earn more for it, often sleep less. Studies show that higher-income earners sleep less than lower-income ones. That could be because higher-income people are spending more time working, so they have less time for sleep. Additionally, working more is stressful, and stress disrupts sleep. But poor sleep contributes to stress, too. A study in Sleep Health found that a poorer night’s sleep is followed by more stress and distracting thoughts at work. Other studies also find that less and poorer sleep is associated with more conflict and stress the next day. © 2019 The New York Times Company

Keyword: Sleep; Stress
Link ID: 26787 - Posted: 11.04.2019

By Laura Sanders Every 20 seconds, a wave of fresh cerebrospinal fluid rolls into the sleeping brain. These slow, rhythmic blasts, described for the first time in the Nov. 1 Science, may help explain why sleep is so important for brain health. Studies on animals have shown that the fluid, called CSF, can wash harmful proteins, including those implicated in Alzheimer’s disease, out of the brain. The new results give heft to the idea that a similar power wash happens in sleeping people. Researchers studied 13 healthy, young people in an MRI scanner as they fell into non-REM sleep, the type of slumber that takes up most of the night. At the same time, the scientists monitored different sorts of activity in participants’ heads. Electrodes measured the activity of large collections of nerve cells, and functional MRI measured the presence of oxygenated blood that gives energy to those nerve cells. By using a form of rapid fMRI, the team also measured another type of activity — the movements of CSF in the brain. Fast fMRI revealed waves of fresh CSF that flowed rhythmically into the sleeping brains, a pattern that was obvious — and big, says study coauthor Laura Lewis, a neuroscientist and engineer at Boston University. “I’ve never had something jump out at me to this degree,” she says. “It was very striking.” Awake people have small, gentle waves of CSF that are largely linked to breathing patterns. In contrast, the sleep waves were tsunamis. “The waves we saw during sleep were much, much larger, and higher velocity,” Lewis says. © Society for Science & the Public 2000–2019

Keyword: Sleep
Link ID: 26781 - Posted: 11.01.2019

By Vanessa Barbara SÃO PAULO, Brazil — It’s hard to feel normal when you wake up at 4 p.m. every day. No, I’m not a nurse who works the evening shift. No, I’m not the hard-partying heir to a Brazilian agribusiness fortune. And before you think it, I’m not lazy, either — I’ve written seven books so far! I sleep until the late afternoon because I’ve finally learned, after fighting it for years, that it’s better to come across as pathetic than to be always exhausted, depressed or sick. I have a severe case of delayed sleep phase syndrome, a chronic misalignment of the body’s circadian rhythms with the daily light-dark cycle of our environment. The phrase “night owl” doesn’t really do it justice; my natural bedtime is around 6 a.m. While we as a culture are gradually becoming more aware of the many ways that bodies can differ from the norm, much of the world still takes for granted that people sleep at night and are awake during the day. Not me. I miss having lunch. According to conventional wisdom, going to bed early and waking up with the birds is a mere matter of habit and will power. This misconception is widespread, even among doctors. And for a long time, I believed it. I spent years taking melatonin and Ambien in order to fall asleep by 2 a.m.; I used to wake up at 11 a.m. and then spend the rest of the day on stimulants such as Provigil and Ritalin. Yet I was always tired and depressed — the outcome that so often results when we try to force ourselves to be different from what we naturally need to be. The last two decades have seen rapid advances in the field of chronobiology, the study of the biochemical clocks that keep our natural physiological rhythms. The 2017 Nobel Prize in Medicine, for instance, was awarded to three American geneticists for their discoveries of molecular mechanisms controlling the circadian rhythms in fruit flies. © 2019 The New York Times Company

Keyword: Biological Rhythms; Sleep
Link ID: 26776 - Posted: 10.31.2019

By Gretchen Reynolds Taking more steps during the day may be related to better sleep at night, according to an encouraging new study of lifestyle and sleep patterns. The study, which delved into the links between walking and snoozing, suggests that being active can influence how well we sleep, whether we actually exercise or not. Sleep and exercise scientists have long been intrigued and befuddled by the ties between physical activity and somnolence. To most of us, it might seem as if that relationship should be uncomplicated, advantageous and one-way. You work out, grow tired and sleep better that night. But a variety of past studies indicate that the effects of exercise on sleep are more scrambled than that. In some studies, when people work out strenuously, they sleep relatively poorly, suggesting that intense exercise might disrupt slumber. Other experiments have found that the impacts of exertion and sleep work both ways; after a night of ragged sleep, people often report finding their normal workout extra wearing. Past research also has produced conflicting results about whether and how the timing of exercise matters, and if afternoon workouts aid or impair that night’s sleep. Most of these past studies have focused on planned exercise, though, not more incidental, everyday physical activity, and much of the research has involved people with clinical sleep problems, such as insomnia. Little has been known about whether simply moving around more during the day, absent formal exercise, might influence sleep, particularly in people who already tend to sleep fairly well. © 2019 The New York Times Company

Keyword: Sleep
Link ID: 26771 - Posted: 10.30.2019