Researchers at the University of Alaska, Fairbanks have discovered a way to induce hibernation in arctic ground squirrels—by administering a substance that stimulates the brain receptors of adenosine, a molecule involved in slowing nerve cell activity. Induced hibernation could someday be used to preserve the brain functions of human stroke victims, though that’s still a ways off as the current technique only works on the arctic ground squirrels during hibernation season.
What’s the News: Smart clothes might soon be coming into bed with you. A company is developing shirts endowed with a chip that senses the changes in breathing that accompany shifts in sleep phase, to help people track how variables like exercise, coffee intake, and stress affect their sleep.
What’s the News: By videotaping sleepwalkers as they got some shut-eye (with their permission, of course), French and Swiss researchers caught on tape what other studies have deduced through brain recordings and memory tasks: As we sleep, our brains seem to replay what we learned during the day. See an example of a a sleepwalker’s re-enactments here:
How the Heck:
The researchers recruited 19 sleepwalkers and 20 people with sleep behavior disorder, who physically act out their dreams, plus 18 people without any sleep disorders.
All the subjects learned a physical skill: hitting particular buttons arrayed around them in response to different prompts from a computer.
The researchers then videotaped each person as they slept. One of the sleepwalkers lifted her arms during REM sleep and started moving her hands in a familiar pattern: an “obvious and accurate re-enactment of a short fragment of the recently learned sequence of movements,” the researchers wrote.
What’s the Context:
A wholelot of research has suggested that a good night’s sleep can improve memory not just for physical tasks like this one, but for words, facts, pictures, and spatial information.
Most of these studies have compared how sleep-deprived and well-rested people performed on memory tests, or looked at how closely brain activity during sleep resembled brain activity as people learned something new. Watching people who act out their thoughts as they sleep provides a more direct view of what the brain’s up to.
Not So Fast:
Some scientists think that sleep’s impact on memory isn’t as simple as locking down everything we’ve learned. Sleep may only solidify memories when we know we’ll be tested, or may actually help us prune unimportant memories rather than fortify the important ones.
Others aren’t convinced that sleep helps us solidify memories at all; they argue that, at best, we can cement what we’ve learned while sleeping just as well as we can while we’re awake.
Reference: “Evidence for the Re-Enactment of a Recently Learned Behavior during Sleepwalking” Delphine Oudiette et al. doi:10.1371/journal.pone.0018056
Honeybees usually get about eight hours of sleep a night (lucky things!), but what happens when evil researchers keep them up all night?
The first study of sleep in bees, published this week in the Proceedings of the National Academy of Sciences, found that the tired bees lag just like sleep-deprived humans do. Too bad bees don’t have coffee. Says lead researcher Barrett Klein:
“When deprived of sleep, humans typically experience a diminished ability to perform a variety of tasks, including communicating as clearly or as precisely. We found that sleep-deprived honey bees also experienced communication problems. They advertised the direction to a food site less precisely to their fellow bees.” [Daily Mail]
So how do you keep bees awake when they don’t need to cram for a calculus final? You make them magnetic. Klein attached a piece of either steel or non-magnetic metal to the bees’ backs. Then all through the night, the researchers swung a magnet over the hive three times a minute–a device they call the “insominator.” This jostled the bees with the magnetic steel on their backs and kept them from sleeping.
The problem: Scientists want to study our circadian rhythms, our bodies’ internal clocks, and they can do so on the genetic level by examining how gene expression changes throughout the day. But ordinarily that would require sampling a person’s blood or skin multiple times a day, an ordeal few of us would want to endure.
The solution: hair.
Makoto Akashi’s team reports today in the Proceedings of the National Academy of Sciences that hairs, be they from the beard or head, contain the telltale signature of RNA activity that shows when we humans are at our peak activity level for the day.
How can some sleepers doze through anything from the rattle of a jackhammer to the blast of a jet engine? According to a new study, an extra helping of brain activity in the thalamus–a region tied to the senses–may give some people a better chance at blocking sleep-disturbing sounds.
“I hear complaints a lot as a sleep doctor that noises are interrupting people’s sleep all the time,’’ said Dr. Jeffrey M. Ellenbogen, chief of the division of sleep medicine at Harvard Medical School [and co-author of the study]. “What is it in the brain that makes it have less response to noise at night, and how can we enhance that natural occurring brain-based process to help people sleep?” he said. [The New York Times]
Researchers at the Harvard Medical School asked twelve healthy volunteers to spend three nights in a sleep lab. The first night the researchers let them sleep soundly, but monitored their brain activity. The following two nights, they used four speakers aimed at the sleepers’ heads to play sounds of air and car traffic, ringing telephones, and “hospital-based mechanical sounds,” among other things. They found that those people whose thalami produced more high-frequency signals called “sleep spindles” lasted the longest when barraged with noises: the more sleep spindles, apparently, the better the sleep. The study appears today in Current Biology.
Don’t be deceived by the peaceful look of a newborn baby asleep in a crib–that little tyke may actually be hard at work, soaking up information about the world. A new study has found that newborns are capable of a rudimentary form of learning while they’re asleep, which may be an important process, considering that infants spend between 16 to 18 hours a day in the land of Nod.
Researchers recruited one- and two-day-old infants for the study, published in the Proceedings of the National Academy of Sciences. With each sleeping baby, the researchers played a musical tone and followed that by a puff of air to the eyes, a mild annoyance that caused the infant to automatically scrunch up its eyes. As this sequence of events was repeated, the sleeping babies learned to associate the air puff with the tone, and soon began to to tighten their eyelids as soon as they heard the musical note, even if the air puff didn’t follow. Electrodes stuck to their scalps also showed activity in the prefrontal cortex, which is involved in memory. (more…)
We know that skimping on sleep gives many of us heavy eyes and sends us on an early afternoon run for a large coffee (or, for those with an iron stomach who don’t mind ingesting 8,300 percent of our daily value of vitamin B12, an energy drink). But studies out this week outline possibly dire health consequences for depriving ourselves of lengthy slumber.
A small study In the Journal of Clinical Endocrinology and Metabolism says that even a single of night of sleep deprivation can cause the body to show signs of insulin resistance, a warning sign of diabetes. And in the journal Sleep, a long-term study by a different team chillingly suggests that continuously snoozing less than six hours per night can increase your risk for an early death.
First, the insulin study: Esther Donga and colleagues examined nine patients, first after the patients had slept a full eight hours and then again after they’d slept just four. The scientists say that insulin sensitivity was reduced by as much as 25 percent when the patients were sleep deprived.
“Our data indicate that insulin sensitivity is not fixed in healthy (people), but depends on the duration of sleep in the preceding night,” Donga wrote in the study. “In fact it is tempting to speculate that the negative effects of multiple nights of shortened sleep on glucose tolerance can be reproduced, at least in part, by just one sleepless night.” A study by U.S. scientists published last year found that people who slept less than six hours a night were 4.5 times more likely to develop abnormal blood sugar readings in six years compared with those who slept longer [Reuters].
Amid mounting evidence that sleep is key for your memory, researchers published a paper in the journal Science last week suggesting that playing specific sounds while a person sleeps—sounds connected to something that the person is trying to memorize—could help the memory sink in.
The researchers taught people to move 50 pictures to their correct locations on a computer screen. Each picture was accompanied by a related sound — meow for a cat, whirring for a helicopter, for example [The New York Times]. Next the test subjects lay down for a nap, and while they slept the researchers played sounds relating to half the objects. When the subjects woke up, scientists tested them on how well they remembered where each object went. Participants didn’t know they’d been subjected to the sounds while they napped, but they fared better at placing the objects for which they heard sounds in their sleep than those they didn’t.
Lead researcher Ken Paller explains: “While asleep, people might process anything that happened during the day — what they ate for breakfast, television shows they watched, anything…. But we decided which memories our volunteers would activate, guiding them to rehearse some of the locations they had learned an hour earlier” [U.S. News & World Report].
For elephant seals, at least, there is some rest for the weary.
These marine mammals undertake epics migrations of thousands of miles, in which they might not return to land for as long at eight months. But elephant seals don’t have the same talent as whales and dolphins, which can have one hemisphere of their brains sleep while the other stays awake, so marine biologists weren’t sure how the seals managed to doze off while at sea. A new study in Biology Letters, however, suggests the seals might sleep as they drift slowly downward.
Past research had identified certain types of dives that include a period of slow descent that might be a siesta of sorts, for resting or digesting [The New York Times]. So scientists tagged a half-dozen young northern elephant seals off the California coast with instruments that tracked the seals’ positions and modeled their dives in three dimensions.
The monitors revealed that the seals periodically flip onto their backs and slip into slow, spiraling dives. The seals wobble as they drift down, and most of the time their bodies follow circular paths toward the bottom of the sea, said study co-author Russel Andrews…. “[They] resemble a leaf that has dropped from a tree branch and is falling toward the ground, fluttering from side to side,” he said [National Geographic]. It seems likely, the scientists say, that the seals catch a quick nap during these long drifts; in fact, once in a while they strike bottom without even noticing.
Researchers have found a pharmaceutical way to clear some of the cognitive fog that results from a sleepless night. In a new study using lab mice, researchers corrected the memory problems in sleep-deprived mice through a drug that suppressed levels of a certain enzyme in a brain region called the hippocampus, which plays an important role in memory and learning.
The study, published in Nature, helps tease out the specific effects of sleep deprivation on the brain. Says lead researcher Christopher Vecsey: “One of the main problems is that sleep deprivation does a lot of things to the brain, and it’s easy to get caught in a mish-mash of different effects” [Nature News].
Here’s yet another reason to get a good night’s rest: Researchers have found a link between the lack of sleep and the development of Alzheimer’s in mice.
The researchers studied levels of amyloid beta — a protein that accumulates in the brain of people with Alzheimer’s — in mice genetically engineered to have a version of Alzheimer’s disease. Amyloid levels rose in the brain when the mice were awake, and fell when they slept. When the researchers prevented the mice from sleeping, it made matters worse [Reuters]. Sleep deprivation accelerated the formation of plaques made of amyloid beta, they found.
The study, published in Science, may lead to other studies that examine whether people with chronic sleep problems are more likely to develop Alzheimer’s. Says lead researcher Jae-Eun Kang: “The hope would be to show that treating sleep problems in humans is important not just for the immediate effect of having a normal life, but also for the long-term effect of having a healthier brain” [Bloomberg].
Some lucky people don’t groan awake to the alarm clock when they’ve only gotten six hours of sleep–instead they pop out of bed, bright-eyed and invigorated and ready for a new day. Now, researchers investigating the phenomenon of people who don’t need as much sleep as the rest of us have found a rare genetic mutation that accounts for some cases of shortened sleep cycles.
The scientists were searching the samples for variations in several genes thought to be related to the sleep cycle. In what amounts to finding a needle in a haystack, they spotted two DNA samples with abnormal copies of a gene called DEC2, which is known to affect circadian rhythms [The New York Times]. When they looked up the volunteers who had given the two DNA samples, they found a mother and daughter who habitually get about six hours of sleep each night and report no ill effects.
Researchers have found good evidence that the troubling sleep disorder narcolepsy is an autoimmune disease, in which the body’s own immune system attacks healthy brain cells. A new study published in Nature Genetics links narcolepsy to mutations of two genes involved in critical roles in protecting the body from disease. These two variations, they say, are likely conspirators against [cells that produce] hypocretin, a hormone that promotes wakefulness, and that narcoleptics have been found to lack [HealthDay News].
Narcolepsy is a disruptive disorder that can trigger “sleep attacks” without any warning during any normal activity. In addition, some people can experience “cataplexy”, where strong emotions such as anger, surprise, or laughter can trigger an instant loss of muscle strength, which, in some cases, can cause collapse [BBC News]. There is currently no cure for narcolepsy, although the symptoms can be largely controlled with a mix of stimulants and sleep-suppressing medications.
80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles on the day's most compelling topics.
80beats is written by Veronique Greenwood and Valerie Ross. This team darts through each day's science news faster than the ruby-throated hummingbird that beats its wings 80 times per second. Send ideas, tips, suggestions, and complaints to [azeeberg at discovermagazine dot com].
The problem: Scientists want to study our 
Don’t be deceived by the peaceful look of a newborn baby asleep in a crib–that little tyke may actually be hard at work, soaking up information about the world. A new study has found that newborns are capable of a rudimentary form of 
We know that skimping on sleep gives many of us heavy eyes and sends us on an early afternoon run for a large coffee (or, for those with an iron stomach who don’t mind ingesting 
Amid mounting evidence that sleep is key for your 
For elephant seals, at least, there is some rest for the weary.
Researchers have found a pharmaceutical way to clear some of the cognitive fog that results from a sleepless night. In a new study using lab mice, researchers corrected the memory problems in 
Here’s yet another reason to get a good night’s rest: Researchers have found a link between the lack of 
Some lucky people don’t groan awake to the alarm clock when they’ve only gotten six hours of 
Researchers have found good evidence that the troubling 
