How sleep deprivation can harm the brain

Not only does a lack of sleep make you feel awful, research has shown it impairs the brain. What's more, sleep loss over long periods can even increase risk for Alzheimer's and other neurological diseases. Researchers want to understand how sleep deprivation causes this harm. In a new study in ACS' Journal of Proteome Research, a team working with mice has identified a protective protein whose level declines with sleep deprivation, leading to neuronal death.

Studies indicate that lack of sleep leads to neurological damage in the hippocampus, a part of the brain involved in learning and memory. To better understand the changes responsible for this effect, scientists have begun examining shifts in the abundance of proteins and RNA, which contains genetically encoded instructions derived from DNA. In this way, previous studies have identified some factors linking sleep loss to damage; however, researchers haven't generally confirmed they play a role in cognitive function within larger animal populations. So, Fuyi Xu, Jia Mi and their colleagues set out to further explore how sleep loss damages the brain and to corroborate their findings.

To start off, the researchers evaluated how well mice navigated a simple maze and learned to recognize new objects after having been sleep deprived for two days. They then extracted the proteins in the animals' hippocampi and identified those whose abundance changed. Then, to further narrow the possibilities, they looked at data linking these proteins to maze performance in related strains of mice that had not experienced sleep deprivation.

This approach led the researchers to pleiotrophin (PTN), which declined in the sleep-deprived mice. Through an analysis of RNA, the team identified the molecular pathway by which a loss of PTN causes cells in the hippocampus to die. When they looked at genetic studies in humans, they found that PTN is implicated in Alzheimer's and other neurodegenerative diseases. This research has uncovered a new mechanism by which sleep protects brain function, according to the researchers, who also note that PTN levels could serve as an indicator of cognitive impairment resulting from insomnia.

From Science Daily

Sleepless and selfish: Lack of sleep makes us less generous

Humans help each other -- it's one of the foundations of civilized society. But a new study by scientists at the University of California, Berkeley, reveals that a lack of sleep blunts this fundamental human attribute, with real-world consequences.

Lack of sleep is known to be associated with an increased risk of cardiovascular disease, depression, diabetes, hypertension and overall mortality. However, these new discoveries show that a lack of sleep also impairs our basic social conscience, making us withdraw our desire and willingness to help other people.

In one portion of the new study, the scientists showed that charitable giving in the week after the beginning of Daylight Saving Time, when residents of most states "spring forward" and lose one hour of their day, dropped by 10% -- a decrease not seen in states that do not change their clocks or when states return to standard time in the fall.

The study, led by UC Berkeley research scientist Eti Ben Simon and Matthew Walker, a UC Berkeley professor of psychology, adds to a growing body of evidence demonstrating that inadequate sleep not only harms the mental and physical well-being of an individual, but also compromises the bonds between individuals -- and even the altruistic sentiment of an entire nation.

"Over the past 20 years, we have discovered a very intimate link between our sleep health and our mental health. Indeed, we've not been able to discover a single major psychiatric condition in which sleep is normal," Walker said. "But this new work demonstrates that a lack of sleep not only damages the health of an individual, but degrades social interactions between individuals and, furthermore, degrades the very fabric of human society itself. How we operate as a social species -- and we are a social species -- seems profoundly dependent on how much sleep we are getting."

"We're starting to see more and more studies, including this one, where the effects of sleep loss don't just stop at the individual, but propagate to those around us," said Ben Simon. "If you're not getting enough sleep, it doesn't just hurt your own well-being, it hurts the well-being of your entire social circle, including strangers."

Ben Simon, Walker and colleagues Raphael Vallat and Aubrey Rossi will publish their results August 23 in the open access journal PLOS Biology. Walker is the director of the Center for Human Sleep Science. He and Ben Simon are members of the Helen Wills Neuroscience Institute at UC Berkeley.

Sleeplessness dampens theory of mind network

The new report describes three separate studies that assessed the impact of sleep loss on people's willingness to help others. In the first study, the scientists placed 24 healthy volunteers in a functional magnetic resonance imager (fMRI) to scan their brains after eight hours of sleep and after a night of no sleep. They found that areas of the brain that form the theory of mind network, which is engaged when people empathize with others or try to understand other people's wants and needs, were less active after a sleepless night.

"When we think about other people, this network engages and allows us to comprehend what other person's needs are: What are they thinking about? Are they in pain? Do they need help?" Ben Simon said. "However, this network was markedly impaired when individuals were sleep deprived. It's as though these parts of the brain fail to respond when we are trying to interact with other people after not getting enough sleep."

In a second study, they tracked more than 100 people online over three or four nights. During this time, the researchers measured the quality of their sleep -- how long they slept, how many times they woke up -- and then assessed their desire to help others, such as holding an elevator door open for someone else, volunteering or helping an injured stranger on the street.

"Here, we found that a decrease in the quality of someone's sleep from one night to the next predicted a significant decrease in the desire to help other people from one subsequent day to the next," Ben Simon said. "Those with poor sleep the night prior were the ones that reported being less willing and keen to help others the following day."

The third part of the study involved mining a database of 3 million charitable donations in the United States between 2001 and 2016. Did the number of donations change after the transition to Daylight Saving Time and the potential loss of an hour of sleep? They found a 10% drop in donations. This same dent in compassionate gift-giving was not seen in regions of the country that did not change their clocks.

"Even a very modest 'dose' of sleep deprivation -- here, just the loss of one single hour of sleep opportunity linked to daylight saving time -- has a very measurable and very real impact on people's generosity and, therefore, how we function as a connected society," Walker said. "When people lose one hour of sleep, there's a clear hit on our innate human kindness and our motivation to help other people in need."

An earlier study by Walker and Ben Simon showed that sleep deprivation forced people to socially withdraw and become more socially isolated. A lack of sleep also increased their feelings of loneliness. Worse still, when those sleep-deprived individuals interacted with other people, they spread their loneliness to those other individuals, almost like a virus, Walker said.

"Looking at the big picture, we're starting to see that a lack of sleep results in a quite asocial and, from a helping perspective, anti-social individual, which has manifold consequences to how we live together as a social species," he said. "A lack of sleep makes people less empathetic, less generous, more socially withdrawn, and it's infectious -- there is contagion of loneliness."

"The realization that the quantity and quality of sleep affects an entire society, caused by an impairment in prosocial behavior, may provide insights into our societal state of affairs in the present day," Walker added.

This finding also offers a novel approach to improving these specific aspects of our society.

"Promoting sleep, rather than shaming people for sleeping enough, could very palpably help shape the social bonds we all experience every day," Ben Simon said.

"Sleep, it turns out, is an incredible lubricant to prosocial, connected, empathic, kind and generous human behavior. In these divisive times, if there was ever a need for a strong, prosocial lubricant to enable the very best version of ourselves within society, now seems to be it," said Walker, author of the international bestseller, Why We Sleep. "Sleep may be a wonderful ingredient that enables the alacrity of helping between human beings."

"Sleep is essential for all aspects of our physical, mental and emotional lives," Ben Simon said. "When sleep is undervalued in society, not only do we get sleep-deprived doctors, nurses and students, but we also suffer from unkind and less empathic interactions on a daily basis."

Read more at Science Daily

Scrap the nap: Study shows short naps don’t relieve sleep deprivation

A nap during the day won't restore a sleepless night, says the latest study from Michigan State University's Sleep and Learning Lab.

"We are interested in understanding cognitive deficits associated with sleep deprivation. In this study, we wanted to know if a short nap during the deprivation period would mitigate these deficits," said Kimberly Fenn, associate professor of MSU, study author and director of MSU's Sleep and Learning Lab. "We found that short naps of 30 or 60 minutes did not show any measurable effects."

The study was published in the journal Sleep and is among the first to measure the effectiveness of shorter naps -- which are often all people have time to fit into their busy schedules.

"While short naps didn't show measurable effects on relieving the effects of sleep deprivation, we found that the amount of slow-wave sleep that participants obtained during the nap was related to reduced impairments associated with sleep deprivation," Fenn said.

Slow-wave sleep, or SWS, is the deepest and most restorative stage of sleep. It is marked by high amplitude, low frequency brain waves and is the sleep stage when your body is most relaxed; your muscles are at ease, and your heart rate and respiration are at their slowest.

"SWS is the most important stage of sleep," Fenn said. "When someone goes without sleep for a period of time, even just during the day, they build up a need for sleep; in particular, they build up a need for SWS. When individuals go to sleep each night, they will soon enter into SWS and spend a substantial amount of time in this stage."

Fenn's research team -- including MSU colleague Erik Altmann, professor of psychology, and Michelle Stepan, a recent MSU alumna currently working at the University of Pittsburgh -- recruited 275 college-aged participants for the study.

The participants completed cognitive tasks when arriving at MSU's Sleep and Learning Lab in the evening and were then randomly assigned to three groups: The first was sent home to sleep; the second stayed at the lab overnight and had the opportunity to take either a 30 or a 60 minute nap; and the third did not nap at all in the deprivation condition.

The next morning, participants reconvened in the lab to repeat the cognitive tasks, which measured attention and placekeeping, or the ability to complete a series of steps in a specific order without skipping or repeating them -- even after being interrupted.

"The group that stayed overnight and took short naps still suffered from the effects of sleep deprivation and made significantly more errors on the tasks than their counterparts who went home and obtained a full night of sleep," Fenn said. "However, every 10-minute increase in SWS reduced errors after interruptions by about 4%."

These numbers may seem small but when considering the types of errors that are likely to occur in sleep-deprived operators -- like those of surgeons, police officers or truck drivers -- a 4% decrease in errors could potentially save lives, Fenn said.

"Individuals who obtained more SWS tended to show reduced errors on both tasks. However, they still showed worse performance than the participants who slept," she said.

Read more at Science Daily