Common sleep myths compromise good sleep and health

April 16, 2019

Science Daily/NYU Langone Health / NYU School of Medicine

People often say they can get by on five or fewer hours of sleep, that snoring is harmless, and that having a drink helps you to fall asleep.

These are, in fact, among the most widely held myths about sleeping that not only shape poor habits, but may also pose a significant public health threat, according to a new study publishing online in Sleep Health on April 16.

Researchers from NYU School of Medicine reviewed more than 8,000 websites to identify the 20 most common assumptions about sleep. With a team of sleep medicine experts, they ranked them based on whether each could be dispelled as a myth or supported by scientific evidence, and on the harm that the myth could cause.

"Sleep is a vital part of life that affects our productivity, mood, and general health and well-being," says study lead investigator, Rebecca Robbins, PhD, a postdoctoral research fellow in the Department of Population Health at NYU Langone Health. "Dispelling myths about sleep promotes healthier sleep habits which, in turn, promote overall better health."

The claim by some people that they can get by on five hours of sleep was among the top myths researchers were able to dispel based on scientific evidence. They say this myth also poses the most serious risk to health from long-term sleep deficits. To avoid the effects of this falsehood and others identified in this study, such as the value of taking naps when you routinely have difficulty sleeping overnight, Robbins and her colleagues suggest creating a consistent sleep schedule and spending more time, at least seven hours, asleep.

Another common myth relates to snoring. And while Robbins says snoring can be harmless, it can also be a sign of sleep apnea, a potentially serious sleep disorder in which breathing starts and stops over the course of the night. The authors encourage patients not to dismiss loud snoring, but rather to see a doctor since this sleep behavior may lead to heart stoppages or other illnesses.

The study authors also found sufficient evidence in published studies that, despite beliefs to the contrary, drinking alcoholic beverages before bed is indeed unhealthy for sleep. According to experts, alcohol reduces the body's ability to achieve deep sleep, which people need to function properly.

"Sleep is important to health, and there needs to be greater effort to inform the public regarding this important public health issue," says study senior investigator Girardin Jean Louis, PhD, a professor in the departments of Population Health and Psychiatry at NYU Langone. "For example, by discussing sleep habits with their patients, doctors can help prevent sleep myths from increasing risks for heart disease, obesity, and diabetes."

The researchers acknowledge that some myths still cause disagreement among sleep experts. For instance, although sleeping in on weekends does disrupt the natural circadian rhythm, for people in certain professions, such as shift workers, it may be better for them to sleep in than to get fewer hours of sleep overall. These discrepancies, they say, suggest that further research needs to be done.

https://www.sciencedaily.com/releases/2019/04/190416081414.htm

Split and continuous sleep in teens impact cognition and glucose levels differently

February 22, 2019

Science Daily/Duke-NUS Medical School

Under conditions of insufficient sleep, effects on cognitive performance and morning glucose levels vary depending on how sleep is distributed.

Many adolescent students sleep less than the recommended duration of 8-10 hours a night. It is unclear; however, whether short night sleep combined with an afternoon nap is as good as having the same amount of sleep continuously during the night without a nap. Researchers at Duke-NUS Medical School have demonstrated for the first time that different sleep schedules with the same total sleep opportunity over 24 hours may have dissimilar effects on cognition and glucose levels. This is the first study to gather experimental evidence on the notion that 'what may be appropriate sleep for one health goal may not be for another'.

The handful of studies that examined split sleep schedules with normal total sleep duration in working-age adults found that both schedules yield comparable brain performance. However, no study has looked at the impact of such schedules on brain function and glucose levels together, especially when total sleep is shorter than optimal. The latter is important because of links between short sleep and risk for diabetes.

The researchers measured cognitive performance and glucose levels following a standardized load in students, aged 15-19 years, during two simulated school weeks with short sleep on school days and recovery sleep on weekends. On school days, these students received either continuous sleep of 6.5 hours at night or split sleep (night sleep of 5 hours plus a 1.5-hour afternoon nap).

"We undertook this study after students who were advised on good sleep habits asked if they could split up their sleep across the day and night, instead of having a main sleep period at night," said Prof. Michael Chee, Director of the Centre for Cognitive Neuroscience, Professor of Neuroscience and Behavioral Disorders Programme, Duke-NUS Medical School and one of the study's senior authors. "We found that compared to being able to sleep 9 hours a night, having only 6.5 hours to sleep in 24 hours degrades performance and mood. Interestingly, under conditions of sleep restriction, students in the split sleep group exhibited better alertness, vigilance, working memory and mood than their counterparts who slept 6.5 hours continuously. This finding is remarkable as the measured total sleep duration over 24 hours was actually less in the former group," Prof. Chee added.

However, for glucose tolerance, the continuous schedule appeared to be better. "While 6.5 hours of night sleep did not affect glucose levels, the split sleep group demonstrated a greater increase in blood glucose levels to the standardized glucose load in both simulated school weeks," noted Dr. Joshua Gooley, Associate Professor of Neuroscience and Behavioral Disorders Programme, Principal Investigator at the Centre for Cognitive Neuroscience, Duke-NUS Medical School and the senior co-author of this study.

Although further studies are necessary to see if this finding translates to a higher risk of diabetes later in life, the current findings indicate that beyond sleep duration, different sleep schedules can affect different facets of health and function in directions that are not immediately clear.

Professor Patrick Casey, Senior Vice Dean of Research, Duke-NUS Medical School, commented, "Recent sleep surveys show that Singaporeans are among the world's most sleep deprived people. This is the latest in a series of studies from a team of researchers from the Neuroscience and Behavioural Disorders Programme and Centre for Cognitive Neuroscience that have provided valuable insights into the importance of good sleep."

https://www.sciencedaily.com/releases/2019/02/190222101312.htm