Better sleep habits lead to better college grades

Data on MIT students underscore the importance of getting enough sleep; bedtime also matters

October 1, 2019

Science Daily/Massachusetts Institute of Technology

Two MIT professors have found a strong relationship between students' grades and how much sleep they're getting. What time students go to bed and the consistency of their sleep habits also make a big difference. And no, getting a good night's sleep just before a big test is not good enough -- it takes several nights in a row of good sleep to make a difference.

Those are among the conclusions from an experiment in which 100 students in an MIT engineering class were given Fitbits, the popular wrist-worn devices that track a person's activity 24/7, in exchange for the researchers' access to a semester's worth of their activity data. The findings -- some unsurprising, but some quite unexpected -- are reported today in the journal Science of Learning in a paper by MIT postdoc Kana Okano, professors Jeffrey Grossman and John Gabrieli, and two others.

One of the surprises was that individuals who went to bed after some particular threshold time -- for these students, that tended to be 2 a.m., but it varied from one person to another -- tended to perform less well on their tests no matter how much total sleep they ended up getting.

The study didn't start out as research on sleep at all. Instead, Grossman was trying to find a correlation between physical exercise and the academic performance of students in his class 3.091 (Introduction to Solid-State Chemistry). In addition to having 100 of the students wear Fitbits for the semester, he also enrolled about one-fourth of them in an intense fitness class in MIT's Department of Athletics, Physical Education, and Recreation, with the help of assistant professors Carrie Moore and Matthew Breen, who created the class specifically for this study. The thinking was that there might be measurable differences in test performance between the two groups.

There wasn't. Those without the fitness classes performed just as well as those who did take them. "What we found at the end of the day was zero correlation with fitness, which I must say was disappointing since I believed, and still believe, there is a tremendous positive impact of exercise on cognitive performance," Grossman says.

He speculates that the intervals between the fitness program and the classes may have been too long to show an effect. But meanwhile, in the vast amount of data collected during the semester, some other correlations did become obvious. While the devices weren't explicitly monitoring sleep, the Fitbit program's proprietary algorithms did detect periods of sleep and changes in sleep quality, primarily based on lack of activity.

These correlations were not at all subtle, Grossman says. There was essentially a straight-line relationship between the average amount of sleep a student got and their grades on the 11 quizzes, three midterms, and final exam, with the grades ranging from A's to C's. "There's lots of scatter, it's a noisy plot, but it's a straight line," he says. The fact that there was a correlation between sleep and performance wasn't surprising, but the extent of it was, he says. Of course, this correlation can't absolutely prove that sleep was the determining factor in the students' performance, as opposed to some other influence that might have affected both sleep and grades. But the results are a strong indication, Grossman says, that sleep "really, really matters."

"Of course, we knew already that more sleep would be beneficial to classroom performance, from a number of previous studies that relied on subjective measures like self-report surveys," Grossman says. "But in this study the benefits of sleep are correlated to performance in the context of a real-life college course, and driven by large amounts of objective data collection."

The study also revealed no improvement in scores for those who made sure to get a good night's sleep right before a big test. According to the data, "the night before doesn't matter," Grossman says. "We've heard the phrase 'Get a good night's sleep, you've got a big day tomorrow.' It turns out this does not correlate at all with test performance. Instead, it's the sleep you get during the days when learning is happening that matter most."

Another surprising finding is that there appears to be a certain cutoff for bedtimes, such that going to bed later results in poorer performance, even if the total amount of sleep is the same. "When you go to bed matters," Grossman says. "If you get a certain amount of sleep -- let's say seven hours -- no matter when you get that sleep, as long as it's before certain times, say you go to bed at 10, or at 12, or at 1, your performance is the same. But if you go to bed after 2, your performance starts to go down even if you get the same seven hours. So, quantity isn't everything."

Quality of sleep also mattered, not just quantity. For example, those who got relatively consistent amounts of sleep each night did better than those who had greater variations from one night to the next, even if they ended up with the same average amount.

This research also helped to provide an explanation for something that Grossman says he had noticed and wondered about for years, which is that on average, the women in his class have consistently gotten better grades than the men. Now, he has a possible answer: The data show that the differences in quantity and quality of sleep can fully account for the differences in grades. "If we correct for sleep, men and women do the same in class. So sleep could be the explanation for the gender difference in our class," he says.

More research will be needed to understand the reasons why women tend to have better sleep habits than men. "There are so many factors out there that it could be," Grossman says. "I can envision a lot of exciting follow-on studies to try to understand this result more deeply."

"The results of this study are very gratifying to me as a sleep researcher, but are terrifying to me as a parent," says Robert Stickgold, a professor of psychiatry and director of the Center for Sleep and Cognition at Harvard Medical School, who was not connected with this study. He adds, "The overall course grades for students averaging six and a half hours of sleep were down 50 percent from other students who averaged just one hour more sleep. Similarly, those who had just a half-hour more night-to-night variation in their total sleep time had grades that dropped 45 percent below others with less variation. This is huge!"

Stickgold says "a full quarter of the variation in grades was explained by these sleep parameters (including bedtime). All students need to not only be aware of these results, but to understand their implication for success in college. I can't help but believe the same is true for high school students." But he adds one caution: "That said, correlation is not the same as causation. While I have no doubt that less and more variable sleep will hurt a student's grades, it's also possible that doing poorly in classes leads to less and more variable sleep, not the other way around, or that some third factor, such as ADHD, could independently lead to poorer grades and poorer sleep."

https://www.sciencedaily.com/releases/2019/10/191001083956.htm

More Americans struggle to fall asleep, stay asleep

November 12, 2019

Science Daily/Iowa State University

If you have trouble sleeping, you're not alone. New research finds more Americans have trouble falling asleep and staying asleep. The difficulties were most prevalent in people with healthy sleep length.

Getting the recommended seven to eight hours of sleep every night is a struggle for most people, but even those who do may not have the best sleep.

New research from Iowa State University finds more Americans have trouble falling asleep and staying asleep. The changes were independent of sleep duration, and difficulties were most prevalent in people with healthy sleep length, the findings show. The study, published in the journal Sleep Health, is one of the first to look at how multiple dimensions of sleep health change over time.

Zlatan Krizan, professor of psychology, and his research team analyzed data collected from nearly 165,000 individuals from 2013 to 2017, as part of the National Health Interview Survey. Over the course of five years, adults who reported at least one day a week with difficulty falling asleep increased by 1.43% and those reporting at least one day with trouble staying asleep increased by 2.70%. While the percentages may seem small, Krizan says based on 2018 population estimates this means as many as five million more Americans are experiencing some sleep difficulties.

"Indeed, how long we sleep is important, but how well we sleep and how we feel about our sleep is important in its own right," Krizan said. "Sleep health is a multidimensional phenomenon, so examining all the aspects of sleep is crucial for future research."

What's causing the problems?

Based on the National Health Interview Survey data, ISU researchers cannot say what is contributing to the worsening of sleep quality. However, Garrett Hisler, lead author and former Iowa State graduate student who is now a postdoctoral researcher at the University of Pittsburgh, says technology is likely a factor.

"We know from our previous research there is a correlation between smartphone use and insufficient sleep among teens," Hisler said. "If we're on our phone before bed or we're receiving alerts in the middle of the night that can make it harder to fall asleep and stay asleep throughout the night."

Consistent with other studies, ISU researchers found the average time spent sleeping decreased. Although the number of people who reported waking up and feeling rested also increased, Krizan says this spike was only observed for one year and is less representative of a trend.

Sleep linked to health

By taking a broader look at sleep quality, researchers aim to better understand the link between sleep and health outcomes. In the paper, they explain that sleep duration combined with poor sleep quality can increase the risk for cardiovascular disease, and sleep quality can affect our overall wellbeing.

"We know that how well people sleep is generally very reflective of people's health and may be an indicator of other conditions," Krizan said. "If we want a full picture of the population's health, it's important to measure and track these changes in sleep trends over time."

Krizan says the findings suggest that intervention efforts might be more effective by targeting factors that influence the initiation and maintenance of sleep as well as the length of sleep. More research is needed to identify how changes in sleep duration and other sleep characteristics are related.

https://www.sciencedaily.com/releases/2019/11/191112122625.htm

Healthy Adults May Need Less Sleep as They Age

February 2, 2010

Science Daily/American Academy of Sleep Medicine

A study in the Feb. 1 issue of the journal Sleep suggests that healthy older adults without sleep disorders can expect to have a reduced "sleep need" and to be less sleepy during the day than healthy young adults.

Results show that during a night of eight hours in bed, total sleep time decreased significantly and progressively with age. Older adults slept about 20 minutes less than middle-aged adults, who slept 23 minutes less than young adults. The number of awakenings and the amount of time spent awake after initial sleep onset increased significantly with age, and the amount of time spent in deep, slow-wave sleep decreased across age groups. Yet even with these decreases in sleep time, intensity and continuity, older adults displayed less subjective and objective daytime sleep propensity than younger adults.

Furthermore, two additional nights involving experimental disruption of slow-wave sleep led to a similar response in all age groups. Daytime sleep propensity increased, and slow-wave sleep rebounded during a night of recovery sleep. According to the authors, this suggests that the lack of increased daytime sleepiness in the presence of an age-related deterioration in sleep quality cannot be attributed to unresponsiveness to variations in homeostatic sleep pressure. Instead, healthy aging appears to be associated with reductions in the sleep duration and depth required to maintain daytime alertness.

"Our findings reaffirm the theory that it is not normal for older people to be sleepy during the daytime," said principal investigator Derk-Jan Dijk, PhD, professor of sleep and physiology at the University of Surrey in the U.K. "Whether you are young or old, if you are sleepy during the day you either don't get enough sleep or you may suffer from a sleep disorder."

The study was conducted at the Clinical Research Centre of the University of Surrey and involved 110 healthy adults without sleep disorders or sleep complaints; 44 were young (20 to 30 years), 35 were middle-aged (40 to 55 years) and 31 were older adults (66 to 83 years). After an eight-hour baseline sleep test, subjects were randomized to two nights with or without selective slow-wave sleep disruption by acoustic stimuli, followed by one recovery night. Nighttime sleep was evaluated by polysomnography, while sleep propensity was assessed using the Multiple Sleep Latency Test (MSLT) and the Karolinska Sleepiness Scale.

During the baseline night, mean objective total sleep time decreased from 433.5 minutes for young adults to 409.9 minutes for middle-aged adults and 390.4 minutes for older adults. Average minutes of slow-wave sleep decreased from 118.4 minutes for young adults to 85.3 minutes for middle-aged adults and 84.2 minutes for older adults. Mean number of minutes spent awake after initial sleep onset increased from 21 for young adults to 49.9 for middle-aged adults and 70.7 for older adults.

Objective daytime sleepiness measured by the MSLT decreased with age. When asked to lie in a comfortable position on the bed and try to fall asleep, young adults fell asleep in an average of 8.7 minutes, compared with 11.7 minutes for middle-aged adults and 14.2 minutes for older adults.

The authors noted that the cause of the age-related reductions in slow-wave sleep and sleep need still must be established. Related factors could include alterations in reproductive hormones or changes in the brain. They added that the study did not address sleep propensity during the evening hours, when it is possible that older adults may be sleepier than young adults.

According to the authors, the study also has implications for the treatment of insomnia in older adults, who may be unaware of their reduced sleep need. Therefore, sleep restriction, which leads to increased homeostatic sleep pressure, may be a successful behavioral therapy for insomnia in healthy older adults.

http://www.sciencedaily.com/releases/2010/02/100201091632.htm

Purpose in life by day linked to better sleep at night

Older adults whose lives have meaning enjoy better sleep quality, less sleep apnea, restless leg syndrome

July 10, 2017

Science Daily/Northwestern University

Having a purpose in life means you are more likely to sleep better at night with less sleep apnea and restless leg syndrome, reports a new study. Cultivating a purpose in life could be drug-free strategy to improve sleep, scientists said. The study participants were older adults -- who tend to have more insomnia and sleep disturbances -- but researchers said the findings are likely applicable to the broader public.

Having a good reason to get out of bed in the morning means you are more likely to sleep better at night with less sleep apnea and restless leg syndrome, reports a new Northwestern Medicine and Rush University Medical Center study based on older adults.

This is the first study to show having a purpose in life specifically results in fewer sleep disturbances and improved sleep quality and over a long period of time. Previous research showed having a purpose in life generally improves overall sleep when measured at a single point in time.

Although the participants in the study were older, researchers said the findings are likely applicable to the broader public.

"Helping people cultivate a purpose in life could be an effective drug-free strategy to improve sleep quality, particularly for a population that is facing more insomnia," said senior author Jason Ong, an associate professor of neurology at Northwestern University Feinberg School of Medicine. "Purpose in life is something that can be cultivated and enhanced through mindfulness therapies."

The paper will be published in the journal Sleep Science and Practice.

Individuals have more sleep disturbances and insomnia as they get older. Clinicians prefer to use non-drug interventions to improve patients' sleep, a practice now recommended by the American College of Physicians as a first line treatment for insomnia, Ong said.

The next step in the research should be to study the use of mindfulness-based therapies to target purpose in life and resulting sleep quality, said Arlener Turner, the study's first author and a former postdoctoral fellow in neurology at Feinberg.

The 823 participants -- non-demented individuals 60 to 100 years old with an average age of 79 -- were from two cohorts at Rush University Medical Center. More than half were African American and 77 percent were female.

People who felt their lives had meaning were 63 percent less likely to have sleep apnea and 52 percent less likely to have restless leg syndrome. They also had moderately better sleep quality, a global measure of sleep disturbance.

For the study, participants answered a 10-question survey on purpose in life and a 32-question survey on sleep. For the purpose in life survey, they were asked to rate their response to such statements as, "I feel good when I think of what I've done in the past and what I hope to do in the future."

The next step in the research should be to study the use of mindfulness-based therapies to target purpose in life and resulting sleep quality, Turner said.

Poor sleep quality is related to having trouble falling asleep, staying asleep and feeling sleepy during the day. Sleep apnea is a common disorder that increases with age in which a person has shallow breathing or pauses in breathing during sleep several times per hour. This disruption often makes a person feel unrefreshed upon waking up and excessively sleepy during the day.

Restless leg syndrome causes uncomfortable sensations in the legs and an irresistible urge to move them. Symptoms commonly occur in the late afternoon or evening hours and are often most severe at night when a person is resting, such as sitting or lying in bed.

https://www.sciencedaily.com/releases/2017/07/170710091734.htm

Deep sleep maintains the learning efficiency of the brain

May 23, 2017
Science Daily/University of Zurich
For the first time, researchers have demonstrated the causal context of why deep sleep is important to the learning efficiency of the human brain. They have developed a new, noninvasive method for modulating deep sleep in humans in a targeted region of the brain.

Most people know from their own experience that just a single sleepless night can lead to difficulty in mastering mental tasks the next day. Researchers assume that deep sleep is essential for maintaining the learning efficiency of the human brain in the long term. While we are awake, we constantly receive impressions from our environment, whereby numerous connections between the nerve cells -- so-called synapses -- are excited and intensified at times. The excitation of the synapses does not normalize again until we fall asleep. Without a recovery phase, many synapses remain maximally excited, which means that changes in the system are no longer possible: Learning efficiency is blocked.

Causal connection between deep sleep and learning efficiency

The connection between deep sleep and learning efficiency has long been known and proven. Now, researchers at the University of Zurich (UZH) and the Swiss Federal Institute of Technology (ETH) in Zurich have been able to demonstrate a causal connection within the human brain for the first time. Reto Huber, professor at the University Children's Hospital Zurich and of Child and Adolescent Psychiatry at UZH, and Nicole Wenderoth, professor in the Department of Health Sciences and Technology at the ETH Zurich, have succeeded in manipulating the deep sleep of test subjects in targeted areas. "We have developed a method that lets us reduce the sleep depth in a certain part of the brain and therefore prove the causal connection between deep sleep and learning efficiency," says Reto Huber.

Subjective sleep quality was not impaired

In the two-part experiment with six women and seven men, the test subjects had to master three different motoric tasks. The concrete assignment was to learn various sequences of finger movements throughout the day. At night, the brain activity of the test subjects during sleep was monitored by EEG. While the test subjects were able to sleep without disturbance after the learning phase on the first day, their sleep was manipulated in a targeted manner on the second day of the experiment -- using acoustic stimulation during the deep sleep phase. To do so, the researchers localized precisely that part of the brain responsible for learning the abovementioned finger movements, i.e., for the control of motor skills (motor cortex). The test subjects were not aware of this manipulation; to them, the sleep quality of both experimental phases was comparable on the following day.

Deep sleep disturbances impair learning efficiency

In a second step, researchers tested how the manipulation of deep sleep affected the motoric learning tasks on the following day. Here, they observed how the learning and performance curves of the test subjects changed over the course of the experiment. As expected, the participants were particularly able to learn the motoric task well in the morning. As the day went on, however, the rate of mistakes rose. After sleep, the learning efficiency considerably improved again. This was not the case after the night with the manipulated sleep phase. Here, clear performance losses and difficulties in learning the finger movements were revealed. Learning efficiency was similarly as weak as on the evening of the first day of the experiment. Through the manipulation of the motor cortex, the excitability of the corresponding synapses was not reduced during sleep. "In the strongly excited region of the brain, learning efficiency was saturated and could no longer be changed, which inhibited the learning of motor skills," Nicole Wenderoth explains.

In a controlled experiment with the same task assignment, researchers manipulated another region of the brain during sleep. In this case, however, this manipulation had no effect on the learning efficiency of the test subjects.

Use in clinical studies planned

The newly gained knowledge is an important step in researching human sleep. The objective of the scientists is to use this knowledge in clinical studies. "Many diseases manifest in sleep as well, such as epilepsy," Reto Huber explains. "Using the new method, we hope to be able to manipulate those specific brain regions that are directly connected with the disease." This could help improve the condition of affected patients.

Science Daily/SOURCE :https://www.sciencedaily.com/releases/2017/05/170523083345.htm