By Michael Schulson Two years ago, at a Stop & Shop in Rhode Island, the Danish neuroscientist and physician Henriette Edemann-Callesen visited an aisle stocked with sleep aids containing melatonin. She looked around in amazement. Then she took out her phone and snapped a photo to send to colleagues back home. “It was really pretty astonishing,” she recalled recently. In Denmark, as in many countries, the hormone melatonin is a prescription drug for treating sleep problems, mostly in adults. Doctors are supposed to prescribe it to children only if they have certain developmental disorders that make it difficult to sleep — and only after the family has tried other methods to address the problem. But at the Rhode Island Stop & Shop, melatonin was available over the counter, as a dietary supplement, meaning it receives slightly less regulatory scrutiny, in some respects, than a package of Skittles. Many of the products were marketed for children, in colorful bottles filled with liquid drops and chewable tablets and bright gummies that look and taste like candy. A quiet but profound shift is underway in American parenting, as more and more caregivers turn to pharmacological solutions to help children sleep. What makes that shift unusual is that it’s largely taking place outside the traditional boundaries of health care. Instead, it’s driven by the country’s sprawling dietary supplements industry, which critics have long said has little regulatory oversight — and which may get a boost from Secretary of Health and Human Services Robert F. Kennedy Jr., who is widely seen as an ally to supplement makers. Thirty years ago, few people were giving melatonin to children, outside of a handful of controlled experiments. Even as melatonin supplements grew in popularity among adults in the late 1990s in the United States and Canada, some of those products carried strict warnings not to give them to younger people. But with time, the age floor dropped, and by the mid-2000s, news reports and academic surveys suggest some early adopters were doing just that. (Try it for ages 11-and-up only, one CNN report warned at the time.) By 2013, according to a Wall Street Journal article, a handful of companies were marketing melatonin products specifically for kids.

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 13: Memory and Learning
Link ID: 29740 - Posted: 04.12.2025

By Lynne Peeples Living things began tracking the incremental passage of time long before the human-made clock lent its hands. As life grew in harmony with the sun’s daily march through the sky, and with the seasons, phases of the moon, tides, and other predictable environmental cycles, evolution ingrained biology with the timekeeping tools to keep a step ahead. It gifted an ability to anticipate changes, rather than respond to them, and an internal nudge to do things when most advantageous and to avoid doing things when not so advantageous. Of course, that optimal timing depended on a species’ niche on the 24-hour clock. When mammals first arose, for example, they were nocturnal — most active during the hours that the dinosaurs slept. Now mammals occupy both their choice territories on a spinning planet and their preferred space on a rotating clock. Timing is everything when it comes to seeking and digesting food, storing food, avoiding becoming food, dodging exposure to DNA-damaging ultraviolet radiation, and many more vital activities, such as navigating, migrating, and reproducing. Take the Eudyptula minor, a tiny penguin species that lives on Phillip Island in Australia. The slate-blue plumaged seabird speed waddles from the ocean to burrow home at the same “sun time” each day — just after sunset. Finding that precise window between day and night maximizes the penguins’ fishing time, allows them enough light to see their way to their burrows, and minimizes the chances they become visible food along the way for nighttime predators, such as orcas, seabirds, and feral cats. An internal clock off by just 10 minutes could prove fatal, one source told me. The island’s tourism industry capitalizes on this predictable “Penguin Parade.” A website lists approximate penguin arrival times for every month of the year and sells tickets to witness the spectacle. A higher ticket price grants visitors access to an underground viewing structure where they can watch the procession of waddlers at eye level. In October 2022, lucky visitors got to view a record-breaking 5,440 little penguins storm the shore and hurry home.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 29549 - Posted: 11.09.2024

Anna Bawden The idea that night owls who don’t go to bed until the early hours struggle to get anything done during the day may have to be revised. It turns out that staying up late could be good for our brain power as research suggests that people who identify as night owls could be sharper than those who go to bed early. Researchers led by academics at Imperial College London studied data from the UK Biobank study on more than 26,000 people who had completed intelligence, reasoning, reaction time and memory tests. They then examined how participants’ sleep duration, quality, and chronotype (which determines what time of day we feel most alert and productive) affected brain performance. They found that those who stay up late and those classed as “intermediate” had “superior cognitive function”, while morning larks had the lowest scores. Going to bed late is strongly associated with creative types. Artists, authors and musicians known to be night owls include Henri de Toulouse-Lautrec, James Joyce, Kanye West and Lady Gaga. But while politicians such as Margaret Thatcher, Winston Churchill and Barack Obama famously seemed to thrive on little sleep, the study found that sleep duration is important for brain function, with those getting between seven and nine hours of shut-eye each night performing best in cognitive tests. © 2024 Guardian News & Media Limited

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 13: Memory and Learning
Link ID: 29389 - Posted: 07.11.2024

By Carl Zimmer Earlier this month, millions of Americans looked up at the sky to witness a total eclipse. Now, another cyclical marvel has arrived, this time at our feet. Trillions of noisy, red-eyed insects called cicadas are emerging from the earth after more than a decade of feeding on tree roots. The United States is home to 15 cicada broods, and in most years at least one of them emerges. This spring, Brood XIX, known as the Great Southern Brood, and Brood XIII, or the Northern Illinois Brood, are emerging simultaneously. Cicada watchers have spotted the first insects coming out of the ground, reporting their sightings to apps such as iNaturalist and Cicada Safari. The Great Southern Brood, which emerges across the South and the Midwest every 13 years, has been seen at sites scattered from North Carolina to Georgia. The Northern Illinois Brood, which appears every 17 years in the Midwest, is expected to appear in the next month, as temperatures there warm. How cicadas manage to rise en masse after spending so long underground remains largely a mystery. “There’s surprisingly little information about cicadas that you’d like to know,” said Raymond Goldstein, a physicist at the University of Cambridge. Once a brood climbs out of the ground, the cicadas crawl up trees to mate, and the females lay eggs in tree branches. After hatching, the young insects drop to earth and burrow into the soil. Then, each cicada spends the next 13 or 17 years underground before emerging to mate and repeat the cycle. That means that trillions of insects have to track the passage of time in the soil. It’s possible that they detect annual changes in tree roots. But how can cicadas add up those changes to divine when 13 or 17 years have passed? Scientists cannot say. © 2024 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: 29272 - Posted: 04.26.2024

Kimberly Rosvall Liz Aguilar The total solar eclipse on April 8, 2024, coincides with an exciting time for wild birds. Local birds are singing for mates and fighting for territories as they gear up for their once-a-year chance to breed. Tens of millions of migrating birds will be passing through the path of totality, and they mostly migrate at night. Because birds use light to match their behaviors to their environment, scientists like us have lots of questions about how they will respond to the eclipse. Will they pause their fighting and wooing and shift toward bedtime-like behaviors? How about a nocturnal animal like an owl or those nighttime migrants – will they start to rustle from their roosts before they realize it’s not night? As behavioral biologists at Indiana University, we research wild breeding birds, with a goal of understanding why animals behave the way that they do in response to environmental challenges and opportunities. For the 2024 eclipse, our team is launching a new project and developing an app. If everything goes as planned, we should end up with a large dataset after the eclipse, collected by community scientist volunteers across the country. On average, a total solar eclipse occurs in the same place only once every 375 years. Most wild animals, like most people, have never seen the sky quickly switch to night in the middle of the day. These rare events are a natural experiment that can help scientists like us understand how animals respond to an unusual sudden change in light. Most past research on animal behavior during total solar eclipses is anecdotal. Observers have reported that zoo animals acted distressed or went into their enclosures. Scientists have spotted spiders starting the nightly deconstruction of their webs in the middle of the day, and farmers have heard their roosters start to crow after totality, as if it’s once again dawn. Other reports suggest more subtle effects on animal behavior. © 2010–2024, The Conversation US, Inc.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 29246 - Posted: 04.06.2024

By Elise Cutts On a summer night in the Bay of Naples, hordes of worms swam upward from the seagrass toward the water’s surface under the light of a waning moon. Not long before, the creatures began a gruesome sexual metamorphosis: Their digestive systems withered, and their swimming muscles grew, while their bodies filled with eggs or sperm. The finger-length creatures, now little more than muscular bags of sex cells, fluttered to the surface in unison and, over a few hours, circled each other in a frantic nuptial dance. They released countless eggs and sperm into the bay — and then the moonlit waltz ended in the worms’ deaths. The marine bristle worm Platynereis dumerilii gets only one chance to mate, so its final dance had better not be a solo. To ensure that many worms congregate at the same time, the species synchronizes its reproductive timing with the cycles of the moon. How can an undersea worm tell when the moon is at its brightest? Evolution’s answer is a precise celestial clock wound by a molecule that can sense moonbeams and sync the worms’ reproductive lives to lunar phases. No one had ever seen how one of these moonlight molecules worked. Recently, however, in a study published in Nature Communications, researchers in Germany determined the different structures that one such protein in bristle worms takes in darkness and in sunlight. They also uncovered biochemical details that help explain how the protein distinguishes between brighter sunbeams and softer moonglow. It’s the first time that scientists have determined the molecular structure of any protein responsible for syncing a biological clock to the phases of the moon. “I’m not aware of another system that has been looked at with this degree of sophistication,” said the biochemist Brian Crane of Cornell University, who was not involved in the new study. © 2023 An editorially independent publication supported by the Simons Foundation.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 29062 - Posted: 12.22.2023

By Carl Zimmer Neanderthals were morning people, a new study suggests. And some humans today who like getting up early might credit genes they inherited from their Neanderthal ancestors. The new study compared DNA in living humans with genetic material retrieved from Neanderthal fossils. It turns out that Neanderthals carried some of the same clock-related genetic variants as do people who report being early risers. Since the 1990s, studies of Neanderthal DNA have exposed our species’ intertwined history. About 700,000 years ago, our lineages split apart, most likely in Africa. While the ancestors of modern humans largely stayed in Africa, the Neanderthal lineage migrated into Eurasia. About 400,000 years ago, the population split in two. The hominins who spread west became Neanderthals. Their cousins to the east evolved into a group known as Denisovans. The two groups lived for hundreds of thousands of years, hunting game and gathering plants, before disappearing from the fossil record about 40,000 years ago. By then, modern humans had expanded out of Africa, sometimes interbreeding with Neanderthals and Denisovans. And today, fragments of their DNA can be found in most living humans. Research carried out over the past few years by John Capra, a geneticist at the University of California, San Francisco, and other scientists suggested that some of those genes passed on a survival advantage. Immune genes inherited from Neanderthals and Denisovans, for example, might have protected them from new pathogens they had not encountered in Africa. Dr. Capra and his colleagues were intrigued to find that some of the genes from Neanderthals and Denisovans that became more common over generations were related to sleep. For their new study, published in the journal Genome Biology and Evolution, they investigated how these genes might have influenced the daily rhythms of the extinct hominins. © 2023 The New York Times Company

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 29052 - Posted: 12.16.2023

Maria Godoy What do you do when you can't get your kids to settle down to go to sleep? For a growing number of parents, the answer is melatonin. Recent research shows nearly one in five school-age children and adolescents are now using the supplement on a regular basis. Pediatricians say that's cause for alarm. "It is terrifying to me that this amount of an unregulated product is being utilized," says Dr. Cora Collette Breuner, a professor of pediatrics at the University of Washington. Melatonin is a hormone produced by your brain that helps regulate sleep-wake cycles. It's also sold as a dietary supplement and is widely used as a sleep aid. Sponsor Message Lauren Hartstein, a postdoctoral researcher who studies sleep in early childhood at the University of Colorado, Boulder, says she first got an inkling of melatonin's growing use in children and adolescents while screening families to participate in research. "All of a sudden last year, we noticed that there was a big uptick in the number of parents who were regularly giving [their kids] melatonin," Hartstein says. Hartstein and her colleagues wanted to learn more about just how widely melatonin is being used in kids. So they surveyed the parents of nearly 1,000 children between the ages of 1 to 14 across the country. She was surprised by just how many kids are taking the supplement. "Nearly 6% of preschoolers, [ages] 1 to 4, had taken it, and that number jumped significantly higher to 18% and 19% for school-age children and pre-teens," she says. As Hartstein and her co-authors recently reported in the journal JAMA Pediatrics, most of the kids that were using melatonin had been on it for a year or longer. And 1 in 4 kids were taking it every single night. © 2023 npr

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 8: Hormones and Sex
Link ID: 29047 - Posted: 12.16.2023

Perspective by Michael Varnum and Ian Hohm A growing body of research in psychology and related fields suggests that winter brings some profound changes in how people think, feel and behave. The natural and cultural changes that come with winter often occur simultaneously, making it challenging to tease apart the causes underlying these seasonal swings. Live well every day with tips and guidance on food, fitness and mental health, delivered to your inbox every Thursday. We recently conducted an extensive survey of these findings with research colleagues Alexandra Wormley, a social psychologist at Arizona State University, and Mark Schaller, a psychologist at the University of British Columbia. Wintertime blues and a long winter’s nap Do you find yourself feeling down in the winter months? You’re not alone. As the days grow shorter, the American Psychiatric Association estimates that about 5 percent of Americans will experience a form of depression known as seasonal affective disorder, or SAD. People experiencing SAD tend to have feelings of hopelessness, decreased motivation to take part in activities they generally enjoy, and lethargy. Even those who don’t meet the clinical threshold for this disorder may see increases in anxiety and depressive symptoms. Scientists link SAD and more general increases in depression in the winter to decreased exposure to sunlight, which leads to lower levels of the neurotransmitter serotonin. Consistent with the idea that sunlight plays a key role, SAD tends to be more common in more northern regions of the world, such as Scandinavia and Alaska, where the days are shortest and the winters longest. Humans, special as we may be, are not unique in showing some of these seasonally linked changes. For instance, our primate relative the Rhesus macaque shows seasonal declines in mood.

Related chapters from BN: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 12: Psychopathology: The Biology of Behavioral Disorders; Chapter 10: Biological Rhythms and Sleep
Link ID: 29043 - Posted: 12.13.2023

Sean O'Donnell Human-driven climate change is increasingly shaping the Earth’s living environments. Rising temperatures, rapid shifts in rainfall and seasonality, and ocean acidification are presenting altered environments to many animal species. How do animals adjust to these new, often extreme, conditions? Animal nervous systems play a central role in both enabling and limiting how they respond to changing climates. Two of my main research interests as a biologist and neuroscientist involve understanding how animals accommodate temperature extremes and identifying the forces that shape the structure and function of animal nervous systems, especially brains. The intersection of these interests led me to explore the effects of climate on nervous systems and how animals will likely respond to rapidly shifting environments. All major functions of the nervous system – sense detection, mental processing and behavior direction – are critical. They allow animals to navigate their environments in ways that enable their survival and reproduction. Climate change will likely affect these functions, often for the worse. Changing temperatures shift the energy balance of ecosystems – from plants that produce energy from sunlight to the animals that consume plants and other animals – subsequently altering the sensory worlds that animals experience. It is likely that climate change will challenge all of their senses, from sight and taste to smell and touch. Animals like mammals perceive temperature in part with special receptor proteins in their nervous systems that respond to heat and cold, discriminating between moderate and extreme temperatures. These receptor proteins help animals seek appropriate habitats and may play a critical role in how animals respond to changing temperatures.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 29007 - Posted: 11.15.2023

Catherine Sweeney - WPLN NASHVILLE, Tenn. — High school classes start so early around this city that some kids get on buses at 5:30 in the morning. Just 10% of public schools nationwide start before 7:30 a.m., according to federal statistics. But in Nashville, classes start at 7:05 — a fact the new mayor, Freddie O'Connell, has been criticizing for years. "It's not a badge of honor," he said when he was still a city council member. Since his election in September, O'Connell has announced that pushing back school start times is a cornerstone of the education policy he is promoting. He and others around the country have been trying to stress that teenagers aren't lazy or to blame for getting too little sleep. It's science. Sponsor Message "All teenagers have this shift in their brain that causes them to not feel sleepy until about 10:45 or 11 at night," said Kyla Wahlstrom, a senior research fellow at the University of Minnesota in the College of Education and Human Development. She studies how education policy affects learning, and she used to be a teacher. "It's a shift that is biologically determined." Sleep deprivation in teenagers is linked to mental health struggles, worse grades, traffic accidents, and more. That's why states including California and Florida have mandated later start times. Individual districts across the country — including some in Tennessee — have made the same change. But resistance to later starts is less about the science than it is about logistical and financial difficulties, especially with basics like busing. Melatonin makes people feel drowsy. The brain starts producing it when it gets dark outside, and its production peaks in the middle of the night. Adolescents' brains start releasing melatonin about three hours later than adults' and younger children's brains, according to the American Chemical Society. When teens wake up early, their brains are still producing melatonin. © 2023 npr

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28995 - Posted: 11.11.2023

By Veronique Greenwood This morning, when the sun came up, billions of humans opened their eyes and admitted into their bodies a shaft of light from space. When the stream of photons struck the retina, neurons fired. And in every organ, in nearly every cell, elaborate machinery stirred. Each cell’s circadian clock, a complex of proteins whose levels rise and fall with the sun, clicked into gear. That clock synchronizes our bodies to the light-dark cycle of the planet by controlling the expression of more than 40% of our genome. Genes for immune signals, brain messengers and liver enzymes, to name just a few, are all transcribed to make proteins when the clock says it’s time. That means you are not, biochemically, the same person at 10 p.m. that you are at 10 a.m. It means that evenings are a more dangerous time to take large doses of the painkiller acetaminophen: Liver enzymes that protect against overdose become scarce then. It means that vaccines given in the morning and evening work differently, and that night-shift workers, who chronically disobey their clocks, have higher rates of heart disease and diabetes. People whose clocks run fast or slow are trapped in a hideous state of perpetual jet lag. “We are linked to this day in ways that I think people just push off,” the biochemist Carrie Partch tells me. If we understand the clock better, she has argued, we might be able to reset it. With that information, we might shape the treatment of diseases, from diabetes to cancer. For more than a quarter century, Partch has lived among the orchestrators of the circadian clock, the proteins whose rise and fall control its workings. As a postdoc, she produced the first visualization of the bound pair of proteins at its heart, CLOCK and BMAL1. Since then, she has continued to make visible the whorls and twists of those and other clock proteins while charting how changes to their structure add or subtract time from the day. Her achievements in pursuit of that knowledge have brought her some of the highest honors in this field of science: the Margaret Oakley Dayhoff Award from the Biophysical Society in 2018, and the National Academy of Sciences Award in Molecular Biology in 2022. Simons Foundation All Rights Reserved © 2023

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28957 - Posted: 10.12.2023

By Virat Markandeya It’s evening at the northern tip of the Red Sea, in the Gulf of Aqaba, and Tom Shlesinger readies to take a dive. During the day, the seafloor is full of life and color; at night it looks much more alien. Shlesinger is waiting for a phenomenon that occurs once a year for a plethora of coral species, often several nights after the full moon. Guided by a flashlight, he spots it: coral releasing a colorful bundle of eggs and sperm, tightly packed together. “You’re looking at it and it starts to flow to the surface,” Shlesinger says. “Then you raise your head, and you turn around, and you realize: All the colonies from the same species are doing it just now.” Some coral species release bundles of a pinkish- purplish color, others release ones that are yellow, green, white or various other hues. “It’s quite a nice, aesthetic sensation,” says Shlesinger, a marine ecologist at Tel Aviv University and the Interuniversity Institute for Marine Sciences in Eilat, Israel, who has witnessed the show during many years of diving. Corals usually spawn in the evening and night within a tight time window of 10 minutes to half an hour. “The timing is so precise, you can set your clock by the time it happens,” Shlesinger says. Moon-controlled rhythms in marine critters have been observed for centuries. There is calculated guesswork, for example, that in 1492 Christopher Columbus encountered a kind of glowing marine worm engaged in a lunar-timed mating dance, like the “flame of a small candle alternately raised and lowered.” Diverse animals such as sea mussels, corals, polychaete worms and certain fishes are thought to synchronize their reproductive behavior by the moon. The crucial reason is that such animals — for example, over a hundred coral species at the Great Barrier Reef — release their eggs before fertilization takes place, and synchronization maximizes the probability of an encounter between eggs and sperm. © 2023 Annual Reviews

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 8: Hormones and Sex
Link ID: 28681 - Posted: 02.25.2023

Jane Clinton For those of us who struggle to leave our beds in the winter, taunts of “lazy” could well be misplaced. New research suggests that while humans do not hibernate, we may need more sleep during the colder months. Analysis of people undergoing sleep studies found that people get more REM (rapid eye movement) sleep in the winter. While total sleep time appeared to be about an hour longer in the winter than the summer, this result was not considered statistically significant. However, REM sleep – known to be directly linked to the circadian clock, which is affected by changing light – was 30 minutes longer in the winter than in summer. The research suggests that even in an urban population experiencing disrupted sleep, humans experience longer REM sleep in winter than summer and less deep sleep in autumn. Researchers say if the study’s findings can be replicated in people with healthy sleep, this would provide the first evidence for a need to adjust sleep habits to season – perhaps by going to sleep earlier in the darker and colder months. Dr Dieter Kunz, corresponding author of the study, based at the Clinic for Sleep & Chronomedicine at the St Hedwig hospital, Germany, said: “Seasonality is ubiquitous in any living being on this planet. “Even though we still perform unchanged over the winter, human physiology is down-regulated, with a sensation of ‘running-on-empty’ in February or March. “In general, societies need to adjust sleep habits including length and timing to season, or adjust school and working schedules to seasonal sleep needs.”

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28672 - Posted: 02.18.2023

Will Stone Maybe this happens to you sometimes, too: You go to bed with some morning obligation on your mind, maybe a flight to catch or an important meeting. The next morning, you wake up on your own and discover you've beat your alarm clock by just a minute or two. What's going on here? Is it pure luck? Or perhaps you possess some uncanny ability to wake up precisely on time without help? It turns out many people have come to Dr. Robert Stickgold over the years wondering about this phenomenon. "This is one of those questions in the study of sleep where everybody in the field seems to agree that's what's obviously true couldn't be," says Stickgold who's a cognitive neuroscientist at Harvard Medical School and Beth Israel Deaconess Medical Center. Stickgold even remembers bringing it up to his mentor when he was just starting out in the field — only to be greeted with a dubious look and a far from satisfactory explanation. "I can assure you that all of us sleep researchers say 'balderdash, that's impossible,' " he says. And yet Stickgold still believes there is something to it. "This kind of precision waking is reported by hundreds and thousands of people,'" he says, including himself. "I can wake up at 7:59 and turn off the alarm clock before my wife wakes up." At least, sometimes. Of course, it's well known that humans have an elegant and intricate system of internal processes that help our bodies keep time. Somewhat shaped by our exposure to sunlight, caffeine, meals, exercise and other factors, these processes regulate our circadian rhythms throughout the roughly 24-hour cycle of day and night, and this affects when we go to bed and wake up. © 2022 npr

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28614 - Posted: 12.28.2022

Ari Daniel Fred Crittenden, 73, lost his sight to retinitis pigmentosa when he was 35 years old. Today he has no visual perception of light. "It's total darkness," he says. Still, he has cells in his eyes that use light to keep his internal clock ticking along nicely. Marta Iwanek for NPR Every baseball season, 73-year-old Fred Crittenden plants himself in front of his television in his small one-bedroom apartment an hour north of Toronto. "Oh, I love my sports — I love my Blue Jays," says Crittenden. "They need me to coach 'em — they'd be winning, I'll tell ya." He listens to the games in his apartment. He doesn't watch them, because he can't see. "I went blind," Crittenden recalls, when "I was 35 years young." Crittenden has retinitis pigmentosa, an inherited condition that led to the deterioration of his retinas. He lost all his rods (the cells that help us see in dim light) and all his cones (the cells that let us see color in brighter light). Within a single year, in 1985, Crittenden says he went from perfect vision to total blindness. Certain cells within Crittenden's retinas that contain melanopsin help his brain to detect light, even if what he sees is darkness. Among other things, these light-detecting cells help his body regulate his sleep cycles. Marta Iwanek for NPR "The last thing I saw clearly," he says, thinking back, "it was my daughter, Sarah. She was 5 years old then. I used to go in at night and just look at her when she was in the crib. And I could just barely still make her out — her little eyes or her nose or her lips or her chin, that kind of stuff. Even to this day it's hard." © 2022 npr

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 7: Vision: From Eye to Brain
Link ID: 28598 - Posted: 12.17.2022

By Dino Grandoni The shrew scampered across the sand, zipping its tiny, velvety body right, left, right, left. In just a few seconds it found the prize concealed in the sandbox: a tasty mixture of earthworms, mealworms and other meat. To quickly solve the puzzle in Dina Dechmann’s lab, the shrew didn’t just need to learn where its meal was hidden. Something else astounding happened in its head. It had to regrow its own brain. “It’s a crazy animal,” said Dechmann, a behavioral ecologist at the Max Planck Institute of Animal Behavior in Germany. “We can learn a lot from the shrews.” To prepare for the depths of winter when food is scarce, many animals slow down, sleep through the cold or migrate to warmer locales. Not the common shrew. To survive the colder months, the animal eats away at its own brain, reducing the organ by as much as a fourth, only to regrow much of brain matter in the spring. The process of shrinking and expanding the brain and other organs with seasons — dubbed Dehnel’s phenomenon — allows animals to reduce calorie-consuming tissue when temperatures drop. Researchers have discovered seasonal shrinkage in the skulls of other small, high-metabolism mammals, including weasels and, most recently, moles. The shrew’s incredible shrinking brain is more than just a biological curiosity. Understanding how these animals are able to restore their brain power may help doctors treat Alzheimer’s, multiple sclerosis and other neurodegenerative diseases in humans. “In the beginning, I couldn’t quite grasp it,” said John Dirk Nieland, an associate professor of health science and technology who is now researching drugs designed to mimic shrews’ brain-altering chemistry in humans.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28580 - Posted: 12.03.2022

By Dino Grandoni The shrew scampered across the sand, zipping its tiny, velvety body right, left, right, left. In just a few seconds it found the prize concealed in the sandbox: a tasty mixture of earthworms, mealworms and other meat. To quickly solve the puzzle in Dina Dechmann’s lab, the shrew didn’t just need to learn where its meal was hidden. Something else astounding happened in its head. It had to regrow its own brain. “It’s a crazy animal,” said Dechmann, a behavioral ecologist at the Max Planck Institute of Animal Behavior in Germany. “We can learn a lot from the shrews.” To prepare for the depths of winter when food is scarce, many animals slow down, sleep through the cold or migrate to warmer locales. Not the common shrew. To survive the colder months, the animal eats away at its own brain, reducing the organ by as much as a fourth, only to regrow much of brain matter in the spring. The process of shrinking and expanding the brain and other organs with seasons — dubbed Dehnel’s phenomenon — allows animals to reduce calorie-consuming tissue when temperatures drop. Researchers have discovered seasonal shrinkage in the skulls of other small, high-metabolism mammals, including weasels and, most recently, moles. The shrew’s incredible shrinking brain is more than just a biological curiosity. Understanding how these animals are able to restore their brain power may help doctors treat Alzheimer’s, multiple sclerosis and other neurodegenerative diseases in humans. “In the beginning, I couldn’t quite grasp it,” said John Dirk Nieland, an associate professor of health science and technology who is now researching drugs designed to mimic shrews’ brain-altering chemistry in humans.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28579 - Posted: 12.03.2022

By Kim Tingley “Time,” when we give it any thought, tends to strike us as extrinsic, a feature of our landscape: We track our passage through it as if traversing an invisible geography, our progress charted by wristwatch, clock, calendar. Humans didn’t invent time, of course, but you might reasonably argue that because we invented the units we use to keep track of it — hours, minutes, seconds — we have every right to tinker with them when we want to. This, at least, was the position the Senate took on March 15, when in a surprise, and surprisingly uncontested, vote it passed the Sunshine Protection Act. The new law would, if the House concurs and the president signs, make daylight saving time permanent, beginning on Nov. 5, 2023. The change has long been a desire of the retail industry because it is convinced that shoppers spend more money when it stays light out later. But lawmakers also seem to have regarded the annual rolling back of the clock as a personal affront: the groggy mornings that result from turning 6 a.m. into 5 a.m., the morale killer for Boston and Billings alike when darkness abruptly descends shortly after 4 in the afternoon. When the yeas prevailed, there was bipartisan applause, as if a particularly hostile foreign adversary had been defeated. What most of those lawmakers very likely didn’t realize was that the enemy was not just outside us — a social agreement about how to label every moment of our existence relative to the sun — it was also inside us, where our internal organs are keeping time, too. In fact, most of our physiological functions are governed by an untold number of carefully synchronized biological clocks that each complete one cycle about every 24 hours. Those cycles are known as circadian rhythms, after the Latin for “about” (circa) and “day” (dies). © 2022 The New York Times Company

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 4: Development of the Brain
Link ID: 28394 - Posted: 07.12.2022

Linda Geddes Science correspondent Summer sunshine can leave us feeling hot, sweaty and a bit burnt – but it may also make men hungrier, by triggering the release of an appetite-boosting hormone from fat stores in their skin, data suggests. The study, which was published in the journal Nature Metabolism, adds to growing evidence that the effects of sun exposure may be more complex than first thought. Excessive exposure is well known to increase the risk of skin cancer, but recent studies have suggested moderate exposure may increase life expectancy, on average, by helping to protect against cardiovascular disease and other causes of death. One possibility is that it lowers blood pressure through the release of nitric oxide from the skin, a process that causes blood vessels to relax. Other scientists have attributed the health benefits of sunlight to vitamin D production. Advertisement Wondering whether food consumption could also provide some clues, Carmit Levy, a professor at Tel Aviv University’s department of human molecular genetics and biochemistry, and his colleagues analysed data from 3,000 participants who were enrolled in a national nutrition survey. The researchers found men but not women increased their food intake during the summer months. The effect was not huge – equivalent to eating an extra 300 calories a day – but over time this could be enough to cause weight gain. To investigate further, they exposed male and female volunteers to 25 minutes of midday sunlight on a clear day, and found it triggered an increase in levels of the appetite-boosting hormone ghrelin in the men’s blood but not in women’s. Experiments in mice similarly found that when males were exposed to UVB rays, they ate more, were more motivated to search for food and had increased levels of ghrelin in their blood. No such change was seen in female mice. The trigger for ghrelin release appeared to be DNA damage in skin cells. Oestrogen blocked this effect, which may be why sunlight did not affect females in the same way. © 2022 Guardian News & Media Limited

Related chapters from BN: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 10: Biological Rhythms and Sleep
Link ID: 28393 - Posted: 07.12.2022