Links for Keyword: Biological Rhythms

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By Amelia Nierenberg Most people think of melatonin as a natural nod-off aid, kind of like chamomile tea in pill form. Even the name of the popular dietary supplement sounds sleepy — that long “o” sound almost makes you yawn mid-word. But melatonin is also a hormone that our brains naturally produce, and hormones, even in minuscule amounts, can have potent effects throughout the body. “There are some clinical uses for it, but not the way that it’s marketed and used by the vast majority of the general public,” said Jennifer Martin, a psychologist and professor of medicine at the University of California, Los Angeles. Experts strongly urge people to consult their doctor or a sleep specialist before taking melatonin, in part because the supplement does not address many underlying health problems that may be disrupting sleep. Anxiety can cause insomnia, as can a host of other potentially serious ailments, such as sleep apnea, restless legs syndrome or mood disorders like depression, that may require medical treatment. Melatonin, however, is relatively inexpensive and readily available at local pharmacies in the United States (in other countries it typically requires a prescription), and many people will go out and buy it on their own. So what’s the best approach to taking melatonin? Here’s what experts had to say. During the day, the brain’s pea-sized pineal gland remains inactive. A few hours before our natural sleep time, as it starts to get dark outside and the light entering our retina fades, the gland switches on to flood the brain with melatonin. “Melatonin is sometimes called the ‘hormone of darkness’ or ‘vampire hormone,’” because it comes out at night, said Matthew Walker, a professor of neuroscience and psychology at the University of California, Berkeley, and the author of the book “Why We Sleep.” As levels of melatonin rise, levels of cortisol, the stress hormone, fall. Respiration slows. Soon, our eyelids begin to droop. Instead of a lights-out trigger, melatonin acts more like a dimmer switch, turning the day functions off and switching night functions on. So taking a melatonin supplement is sort of like taking a dose of sunset, tricking your body into feeling like it’s nighttime. It doesn’t put you to sleep as much as it tells the body that it’s time to sleep. © 2022 The New York Times Company

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28158 - Posted: 01.19.2022

Clare Marie Schneider For some people, waking up early just feels natural. Carla Finley is a baker in Brooklyn, N.Y., who starts her day at 5 or 6 a.m. Finley is what we would call a morning person. "Sometimes it's still dark, which actually I love," she says. "Something about feeling the light come in feels really sacred." This story comes from Life Kit, NPR's family of podcasts to help make life better — covering everything from exercise to raising kids to making friends. For more, sign up for the newsletter and follow @NPRLifeKit on Twitter. Of course, not everyone is as lucky as Finley. Emily Gerard is a writer for the Today show, and she often finds herself waking up at odd hours to prepare for the show, which starts at 7 a.m. "When that alarm goes off, I have a few moments of feeling like I want to die," she says. There are a lot of reasons why we may have to get up early. Maybe it's for work, or maybe it's to get your kids ready for school or take care of a family member. Maybe you just want some time to work on your hobby or take care of errands before a busy day. But if you're not naturally a morning person, how much room do you have to change your wake-up schedule? "We have a fair amount of wiggle room, but it's behavioral," says Dr. Katie Sharkey, an associate professor of medicine and psychiatry and human behavior at Brown University's Alpert Medical School. Basically, your biological clock, which determines your circadian rhythms, is baked into who you are to an extent, but a few habits can help make waking up earlier less of a chore. © 2021 npr

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28063 - Posted: 11.06.2021

By Diana Kwon It’s nearly that time of the year again: the end of daylight saving, when Americans push their clocks back and rejoice at the gained hour of sleep—or mourn the lost hour of sunlight in the afternoon. This system’s twice-a-year transitions have become increasingly unpopular. Scientists have been calling attention to the damaging effects of the time changes—which include a general reduction in mental and physical well-being, as well as a potential increased risk of serious complications, such as strokes and heart attacks, soon after the shifts. There is also evidence of increases in traffic fatalities and harmful medical errors shortly following when clocks are moved forward in the spring. Advertisement In many countries, this might be the one of the last instances in which people make the adjustment. Governments around the world have been in discussions about scrapping the seasonal clock changes and sticking to one time—either permanent standard time or permanent daylight saving. In the U.S., many states are considering, or have already passed, legislation to adopt one of the two. Hawaii and most of Arizona decided to adopt just standard time more than 50 years ago. Last year the European Parliament voted to abolish the time shifts, but the member states of the European Union have yet to agree on how to implement the decision. Beth Malow, a professor of neurology and pediatrics at Vanderbilt University, spoke with Scientific American about the health effects of this timekeeping practice and what should replace it. © 2021 Scientific American,

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28062 - Posted: 11.06.2021

By Jillian Kramer Mice are at their best at night. But a new analysis suggests researchers often test the nocturnal creatures during the day—which could alter results and create variability across studies—if they record time-of-day information at all. Of the 200 papers examined in the new study, more than half either failed to report the timing of behavioral testing or did so ambiguously. Only 20 percent reported nighttime testing. The analysis was published in Neuroscience & Biobehavioral Reviews. West Virginia University neuroscientist Randy Nelson, the study's lead author, says this is likely a matter of human convenience. “It is easier to get students and techs to work during the day than [at] night,” Nelson says. But that convenience comes at a cost. “Time of day not only impacts the intensity of many variables, including locomotor activity, aggressive behavior, and plasma hormone levels,” but changes in those variables can only be observed during certain parts of the diurnal cycle, says University of Wyoming behavioral neuroscientist William D. Todd. This means that “failing to report time of day of data collection and tests makes interpretation of results extremely difficult,” adds Beth Israel Deaconess Medical Center staff scientist Natalia Machado. Neither Todd nor Machado was involved in the new study. The study researchers say it is critical that scientists report the timing of their work and consider the fact that animals' behavioral and physiological responses can vary with the hour. As a first step, Nelson says, “taking care of time-of-day considerations seems like low-hanging fruit in terms of increasing behavioral neuroscience research reliability, reproducibility and rigor.” © 2021 Scientific American

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 1: Introduction: Scope and Outlook
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 27953 - Posted: 08.21.2021

By Nicholas Bakalar If you are a morning person, you may be at reduced risk for major depression, a new study suggests. Several studies of the body’s circadian sleep-wake cycle have shown that being an early bird is associated with a lower risk for depression. But those studies were observational so could not prove cause and effect. For example, people who are early birds may have other health or lifestyle behaviors that reduce their risk for depression — they may have a healthier diet, for example, exercise more, or have fewer health conditions, such as chronic pain, that are associated with depression. All these factors, and many others, could explain the decreased risk for depression, and not the fact of being an early bird. Moreover, depression itself causes sleep disturbances, so it could be that depression is a cause of being a night owl, rather than the other way around. The new study, however, offers more compelling evidence that going to bed early and waking early may, in itself, provide protection against depression, independent of other factors. The study, published in JAMA Psychiatry, uses a research method called Mendelian randomization that helps pinpoint the cause of what may be a cause-and-effect relationship. With Mendelian randomization, researchers can compare large groups of people based on genetic variants that are independent of other health or behavioral characteristics — in this case, the tendency to being a night owl or a morning person, inherited traits that are randomly allocated during our development in the womb. More than 340 genetic variants associated with circadian sleep rhythm have been identified, and the researchers can compare large groups of people with the genetic variants for being a morning person with groups that lack them. Nature has, in essence, set up the randomized experiment for them. © 2021 The New York Times Company

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 27868 - Posted: 06.23.2021

MICHELLE STARR In many parts of the world, people collectively reset their clocks twice a year. Depending on the season, clocks are either wound an hour forwards, or an hour backwards - a practice designed to maximise the overlap between our waking hours and the available daylight. Now, members of the American Academy of Sleep Medicine (AASM) Public Safety Team and Board of Directors have published an advisory calling for the practice of daylight saving to be abolished. "Daylight saving time is less aligned with human circadian biology - which, due to the impacts of the delayed natural light/dark cycle on human activity, could result in circadian misalignment, which has been associated in some studies with increased cardiovascular disease risk, metabolic syndrome and other health risks," they write in the Journal of Clinical Sleep Medicine. "It is, therefore, the position of AASM that these seasonal time changes should be abolished in favour of a fixed, national, year-round standard time." Their paper is focused on the US, citing health statistics connected with the changing of the clocks in spring - from standard time to daylight saving time. This is when the clocks are wound back an hour, so that everyone loses an hour, usually from their sleep schedule. Ostensibly, the major economic reason for daylight saving time (DST) is to reduce energy usage, an effect that has been found to result in savings from 0.5 to 1 percent to a potential energy use increase in some areas as dependence on home heating and cooling rises.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 27458 - Posted: 09.07.2020

Research shows that adolescents who live in areas that have high levels of artificial light at night tend to get less sleep and are more likely to have a mood disorder relative to teens who live in areas with low levels of night-time light. The research was funded by the National Institute of Mental Health (NIMH), part of the National Institutes of Health, and is published in JAMA Psychiatry. “These findings illustrate the importance of joint consideration of both broader environmental-level and individual-level exposures in mental health and sleep research,” says study author Diana Paksarian, Ph.D., a postdoctoral research fellow at NIMH. Daily rhythms, including the circadian rhythms that drive our sleep-wake cycles, are thought to be important factors that contribute to physical and mental health. The presence of artificial light at night can disrupt these rhythms, altering the light-dark cycle that influences hormonal, cellular, and other biological processes. Researchers have investigated associations among indoor artificial light, daily rhythms, and mental health, but the impact of outdoor artificial light has received relatively little attention, especially in teens. In this study, Paksarian, Kathleen Merikangas, Ph.D., senior investigator and chief of the Genetic Epidemiology Research Branch at NIMH, and coauthors examined data from a nationally representative sample of adolescents in the United States, which was collected from 2001 to 2004 as part of the National Comorbidity Survey Adolescent Supplement (NCS-A). The dataset included information about individual-level and neighborhood-level characteristics, mental health outcomes, and sleep patterns for a total of 10,123 teens, ages 13 to 18 years old.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 27348 - Posted: 07.08.2020

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

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and 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

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 26962 - Posted: 01.15.2020

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

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 26852 - Posted: 11.26.2019

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

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 26776 - Posted: 10.31.2019

Patti Neighmond Many American teenagers try to put in a full day of school, homework, after-school activities, sports and college prep on too little sleep. As evidence grows that chronic sleep deprivation puts teens at risk for physical and mental health problems, there is increasing pressure on school districts around the country to consider a later start time. In Seattle, school and city officials recently made the shift. Beginning with the 2016-2017 school year, the district moved the official start times for middle and high schools nearly an hour later, from 7:50 a.m. to 8:45 a.m. This was no easy feat; it meant rescheduling extracurricular activities and bus routes. But the bottom line goal was met: Teenagers used the extra time to sleep in. Researchers at the University of Washington studied the high school students both before and after the start-time change. Their findings appear in a study published Wednesday in the journal Science Advances. They found students got 34 minutes more sleep on average with the later school start time. This boosted their total nightly sleep from 6 hours and 50 minutes to 7 hours and 24 minutes. "This study shows a significant improvement in the sleep duration of students, all by delaying school start times so they're more in line with the natural wake-up times of adolescents," says senior author Horacio de la Iglesia, a University of Washington researcher and professor of biology. The study also found an improvement in grades and a reduction in tardiness and absences.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 4: Development of the Brain
Link ID: 26660 - Posted: 10.01.2019

By Tina Hesman Saey Mice (and maybe people) may metabolize food according to daily, circadian rhythms set by gut bacteria. Microbes in the small intestine of mice rhythmically dictate when fat is taken up by cells that line the organ, researchers report. The study, described in the Sept. 27 Science, details how gut microbes influence a host’s metabolism. If the findings carry over to people, the research may give clues to why jet lag and night-shift work, which can throw off circadian rhythms, often lead to obesity, diabetes and other health problems. Researchers knew that human cells have molecular clocks that time 24-hour circadian cycles of metabolism (SN: 11/8/18), and that gut microbes in the colon follow their hosts’ biological beat (SN: 10/16/14). But the new study finds that, at least in the small intestine, microbes can set rhythms for host cells to follow. That work was done in mice, but the process may work similarly in people. The new research “is helping us appreciate just how intertwined are the metabolisms of the microbiota and their mammalian hosts,” says microbiologist and immunologist Andrew Gewirtz of Georgia State University in Atlanta who was not involved in the work. “It’s a very intimate interaction, regulating things as basic as circadian rhythms, which was quite a surprise.” © Society for Science & the Public 2000–2019.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 26651 - Posted: 09.27.2019

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. My friend, who asked to remain anonymous, has always been an early riser, even as a teenager. Getting up at 5 was an advantage in high school — she never had to worry about being late. But as she aged, her nights kept getting shorter. Now at age 63 she’s ready to go to sleep before 9 p.m., but that rarely fits with the demands of her life. No matter how delayed her bedtime, she gets up by 4 in the morning — and sometimes as early as 1:30 — and can’t get back to sleep. She said that given her stimulating job as an investment products specialist, she’s not sleepy during the day, nor does she nap. Still, she’s concerned about her short nights, partly because she’s read that insufficient sleep — especially not enough REM sleep, when dreams occur — has been linked to a possible increased risk of Alzheimer’s disease. She knows that late dinners, especially with wine, contribute to her sleep problem. But it’s also likely that her lifelong dairy-farmer sleep pattern is programmed by her genes, not the result of unavoidable disruptions or unwise living habits. And, it seems, her early-to-sleep, early-to-wake rhythm may not be as extremely rare as has long been believed. In a new study in the journal Sleep by researchers in San Francisco, Salt Lake City and Madison, Wis., of more than 2,400 patients who visited a sleep clinic for complaints like sleep apnea or insomnia, a small number of them were found to have a previously unrecognized familial form of advanced sleep phase, a kind of permanent jet lag that the study showed often runs in families. © 2019 The New York Times Company

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 4: Development of the Brain
Link ID: 26488 - Posted: 08.12.2019

By Diana Kwon Your brain is a bit like a concert hall. To drive our cognitive processes, several groups of neurons need to become active—and, like the various sections of an orchestra, work in harmony to produce the symphony of computations that allow us to perceive and interact with our surroundings. As with an orchestra, the brain likely requires a conductor to keep all its active parts in sync. There are neuroscientists who think that gamma rhythms, fast brain waves that fluctuate at a frequency of approximately 40 cycles per second, play this role. By ticking at regular intervals, these oscillations are thought to act like a clock that coordinates information transfer from one group of neurons to another. There is ample evidence suggesting that gamma waves are important for the brain's computations: decades of studies in humans and other animals have found these patterns in many parts of brain and have associated them with a range of cognitive processes, such as attention and the mental scratchpad of working memory. Some studies have even linked disturbances in these oscillations to various neurological diseases, including schizophrenia and Alzheimer's. But a consensus does not exist. Some neuroscientists think that these gamma waves may not do much at all. Rather than a relevant physiological signal, one camp believes that these rhythms are simply “an exhaust fume of computation,” says Chris Moore, a neuroscientist at the Carney Institute for Brain Science at Brown University. In the same way your car releases emissions each time you drive it—the gamma signal could be perfectly correlated with brain activity, but not provide any meaningful contribution to the actual function of the car, he explains. © 2019 Scientific American

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 14: Attention and Higher Cognition
Link ID: 26429 - Posted: 07.19.2019

Erin Wayman Crowds of people gather to watch an evening spectacle on beaches in Southern California: Twice a month, typically from March through August, the sand becomes carpeted with hundreds or thousands of California grunion. Writhing, flopping, silvery sardine look-alikes lunge as far onto shore as possible. As the female fish dig their tails into the sand and release eggs, males wrap around females and release sperm to fertilize those eggs. About 10 days later, the eggs hatch and the little grunion get washed out to sea. This mating ritual is set to the tides, with hatching timed to the arrival of the peak high tide every two weeks. But the ultimate force choreographing this dance is the moon. Many people know that the moon’s gravitational tug on the Earth drives the tides, and with them, the life cycles of coastal creatures. Yet the moon also influences life with its light. This story is part of a special report celebrating humans’ enduring fascination with the moon and exploring the many ways it affects life on Earth. More articles will be published in the coming weeks. See all the articles, plus our 1969 coverage of Apollo 11, here. For people living in cities ablaze with artificial lights, it can be hard to imagine how dramatically moonlight can change the nocturnal landscape. Out in the wild, far from any artificial light, the difference between a full moon and a new moon (when the moon appears invisible to us) can be the difference between being able to walk outside without a flashlight and not being able to see the hand in front of your face. |© Society for Science & the Public 2000 - 2019.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 26398 - Posted: 07.08.2019

Bryan Clark Last spring, a study set the internet ablaze with sensational headlines promising an early death for those with nontraditional sleep schedules. It wasn’t the conclusion of the study, or its researchers. But in the bombastic world of science reporting, it didn’t really matter. Originally published in the journal Chronobiology International, the study looked at the chronotypes — a means of classifying one’s predisposition for sleeping at certain hours — of more than 430,000 people over a six-and-a-half-year period. Scouring data from the National Health Service in England and the NHS Central Register in Scotland, researchers sought to find out what, if any, negative health impacts awaited those with a night-owl schedule. After sorting nearly half a million people into four groups — definite larks (larks are early birds, those most likely to rise with the sun), definite owls (those more likely to retire to bed with the sun than to wake with it), moderate larks and moderate owls — researchers reported some troubling findings. More than 10,000 participants died during the study period. Of those deaths, the bulk seemed to be the result of natural causes. The study didn’t necessarily seek to link death with sleep deprivation, but rather to “comorbidity” — the occurrence in one person of two or more conditions, such as psychological or neurological disorders, diabetes and the like. With each incremental shift toward a night-owl schedule, comorbidities became more common, increasing the risk of an early death. But while saying that night owls are going to die early makes for an eye-catching headline, the real story isn’t quite that simple. The story behind the study It’s evident that owls’ nontraditional schedules put them at risk of significant health problems. Nearly every study on this chronotype has returned troubling findings. © 2019 The New York Times Company

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 26267 - Posted: 05.24.2019

By Christopher Ingraham Sleep scientist Matthew Walker has observed that “human beings are the only species that deliberately deprive themselves of sleep for no apparent gain.” We stay up late to watch our favorite TV shows. We wake up early to get to work or school on time. And twice a year we change our clocks, to the bewilderment of our circadian rhythms. We also set up conflicts between our natural and social clocks in other, less obvious ways, a fact underscored in research published this month in the Journal of Health Economics. It turns out, the study found, that living on the wrong side of a time zone’s boundary can have negative consequences on a person’s health and wallet. The culprit? More natural light in the evening hours. To understand the study, co-authored by Osea Giuntella of the University of Pittsburgh and Fabrizio Mazzonna of the Universita della Svizzera Italiana, it is important to understand how time zones affect local sunset times. Traveling east to west, sunrise and sunset times get later, as the map above shows. Panama City, Fla., for instance, is located on the far eastern end of the Central time zone, while Pecos, Tex., sits on the far western side. This week, the sun set in Panama City about 7:12 p.m. Central time. In Pecos, it set more than an hour later, at 8:25 p.m. Sunset is a powerful biological trigger: The fading of natural light causes the body to release melatonin, a hormone that induces drowsiness. As a result, people on the eastern side of a time zone, where the sun sets earlier, tend to go to bed earlier than those on the western side. The data below, derived from about 1 million users of the now-defunct sleep tracker Jawbone, illustrates this point, showing how bedtimes shift from east to west, with a sharp reset happening once you cross into a new time zone. © 1996-2019 The Washington Post

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 26161 - Posted: 04.22.2019

By Steph Yin For animals that hibernate, making it to spring is no small feat. Torpor — the state of reduced bodily activity that occurs during hibernation — is not restful. By the time they emerge, hibernating animals are often sleep-deprived: Most expend huge bursts of energy to arouse themselves occasionally in the winter so their body temperatures don’t dip too low. This back-and-forth is exhausting, and hibernators do it with little to no food and water. By winter’s end, some have shed more than half their body weight. But just because it’s spring doesn’t mean it’s time to celebrate. Spring means getting ready for the full speed of summer — and after spending a season in slow motion, that requires some ramping up. Here’s a look at what different animals have on the agenda after coming out of winter’s slumber. Black bears emerge from their dens in April, but stay lethargic for weeks. During this so-called walking hibernation, they sleep plenty and don’t roam very far. Though they have lost up to one-third of their body weight over winter, they don’t have a huge appetite right away — their metabolism is not yet back to normal. They snack mostly on pussy willows and bunches of snow fleas. In January or February, some females give birth, typically to two or three cubs. New mothers continue to hibernate, but they go in and out of torpor, staying alert enough to respond to their cubs’ cries. When they emerge from their dens, mama bears find trees with rough bark that her cubs can easily climb for safety. © 2019 The New York Times Company

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 26112 - Posted: 04.04.2019

The brain function of very late risers and "morning larks" during the hours of the working day is different, according to a study. Researchers scanned the brains of night owls with a bedtime of 02:30 and a wake time of 10:15, along with early risers. The tests - performed between 08:00 and 20:00 - found night owls had less connectivity in brain regions linked to maintaining consciousness. They also had poorer attention, slower reactions and increased sleepiness. Researchers said it suggested that night owls were disadvantaged by the "constraints" of the typical working day. They called for more research to understand the health implications of night owls performing on a work or school schedule to which they are not naturally suited. Scientists took 38 people who were either night owls or morning larks (people who went to bed just before 23:00 and woke at 06:30) and investigated their brain function at rest using magnetic resonance imaging (MRI) scans. The volunteers then carried out a series of tasks at various times, from 08:00 to 20:00, and were asked to report on their levels of sleepiness. Morning larks were least sleepy and had their fastest reaction time in the early morning tests. They were also found to perform significantly better at this time than night owls. In contrast, night owls were least sleepy and had their fastest reaction time at 20:00, although they did not do significantly better than the larks at this time. The brain connectivity in the regions that predicted better performance and lower sleepiness was significantly higher in larks at all time points, suggesting connectivity in late risers is impaired throughout the whole working day, researchers said. © 2019 BBC

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 25967 - Posted: 02.15.2019