By Carolyn Crist

(Reuters Health) – Widespread beliefs about sleeping include advice on how much sleep is enough, what quality sleep means and how to achieve it, but when these pronouncements are wrong, they can do more harm than good, researchers argue.

The study team gathered the most common sleep “myths” and asked sleep-science experts to rank them according to how wrong they were, and how bad it might be for a person’s health to follow the advice.

“Sleep plays a vital role in our health and wellbeing,” said lead author of the report in Sleep Health, Rebecca Robbins of the New York University School of Medicine in New York City.

“Although there is growing awareness of sleep’s importance, myths – or beliefs that are held despite an evidence base to suggest the beliefs are false – are held among some of our population,” she told Reuters Health by email.

About one third of adults in the U.S. report sleeping less than the recommended seven hours, according to the Centers for Disease Control and Prevention.

Robbins and 10 sleep experts in the fields of sleep research, circadian science, neuroscience and psychiatry compiled a list of 50 potential myths by using web searches of popular press and scientific literature. The experts then rated each one, and the study team narrowed the list to the top 20 sleep myths, based on how false and how significant for public health each was.

The list was further broken down into categories, including myths about sleep duration, sleep timing, sleep behaviors, daytime behaviors affecting sleep, pre-sleep behaviors and brain function during sleep.

When it came to sleep duration, the highest-rated myth was that “being able to fall sleep ‘anytime, anywhere’ is a sign of a healthy sleep system.” Instead, this is more indicative of a chronically sleep-deprived person, the experts said, and excessive daytime sleepiness may be one of the primary symptoms of obstructive sleep apnea.

Other myths in this category were that “many adults need only five or fewer hours of sleep” and “your brain and body can learn to function just as well with less sleep.”

On the other hand, sleep experts said the belief that one night of sleep deprivation doesn’t likely have lasting negative health consequences is true.

Regarding sleep timing, the highest-rated myth was that “it doesn’t matter what time of day you sleep.” Instead, research on night-shift workers points to lower sleep quality, as well as a higher risk for depression, diabetes and cancer, the study team notes.

When the sleep experts ranked myths around sleep behaviors, they considered the worst ones to be, “lying in bed with your eyes closed is almost as good as sleeping” and “if you have difficulty falling asleep, it’s best to stay in bed and try to fall back to sleep.”

Instead, the experts said, cognitive activity when a person is sleeping is distinctly different from being awake with eyes closed. Also, those who can’t fall asleep should leave bed, avoid blue light and return to bed when they’re tired.

Pre-sleep, the experts agreed that alcohol before bed does not improve sleep. Although folklore may encourage a “nightcap,” in fact, alcohol can lead to sleep disturbances during the second part of the night when REM sleep is most valuable. Alcohol consumption can also worsen sleep apnea symptoms for those with a history of snoring.

The sleep experts also refuted the myth that it’s better to have a warmer bedroom than a cooler bedroom, and recommended a temperature between 65 and 70 degrees Fahrenheit (about 18 to 21 degrees C).

They also noted that remembering your dreams isn’t necessarily a sign of good sleep, and sleeping with a pet doesn’t always improve sleep quality, even if it is comforting.

“Knowing what is true and what is a myth will help to support choices linked to sleep hygiene and sleep architecture,” said Sarah Godsell, a public health researcher with the South Gloucestershire Council in the UK, who has studied sleep beliefs and where they originate.

“Sleep is important, so who do you listen to and who influences your sleep behaviors?” Godsell, who wasn’t involved in the current study, said in an email. “Do you know about its key functions and its importance for health and wellbeing?”

SOURCE: Sleep Health, online April 16, 2019.