AHA News: Enjoy a Nap, But Know the Pros and Cons
WEDNESDAY, July 22, 2020 (American Heart Association News) -- You could read this story now. Or you could take a nap first, and perhaps tackle it feeling more alert and refreshed.
Health-wise, is that a good idea?
Under the right conditions, for the right reasons, probably – if you're awake to the possible pitfalls.
"A power nap, between 15 and 45 minutes, can improve memory and reduce fatigue for the rest of the day," said Dr. Michael Grandner, director of the Sleep and Health Research Program at the University of Arizona in Tucson. "If you're otherwise well rested, that kind of nap can actually boost performance pretty well."
Some studies even compare the benefits of a midday nap to a cup of coffee, while some companies – including Google and NASA – let workers pencil naptime into their daily schedule.
But the long-term effects of naps are less conclusive.
For example, a 2019 study in the British medical journal Heart tracked the napping habits of nearly 3,500 people over five years and found those who napped once or twice a week were 48% less likely to have a cardiovascular event than those who didn't. Conversely, a meta-analysis of 11 studies published in the journal Sleep in 2015 showed people who nap for an hour or more a day had 1.82 times the rate of cardiovascular disease than people who didn't nap.
"We do not know enough about the association of naps with either optimal health or disease risk, especially cardiovascular disease," said Dr. Clete Kushida, a neurologist and professor of psychiatry and behavioral sciences at the Stanford University Medical Center in California. "More research needs to be conducted."
The more urgent health question, both experts say, is why you're taking that nap.
"If you're napping because it helps you get through the day, that's probably a good thing," Grandner said. "But if you're napping because you just can't stay awake, that's a sign that there's some underlying health issue. You're either not getting enough sleep at night or your sleep quality could be very poor."
The Centers for Disease Control and Prevention estimates one-third of U.S. adults don't get enough sleep – at least seven hours per night is the standard recommendation – and warns that the risks include heart disease, diabetes, obesity and depression. Even the weary who appear to have slept long enough may have sleep apnea, a common sleep disorder where breathing is frequently interrupted.
"If an individual has significant daytime sleepiness leading to inadvertent or spontaneous naps, it usually indicates sleep quantity or sleep quality issues," Kushida said. If the sleep time seems adequate, he urges an evaluation "for sleep disorders and/or medical diseases."
The ideal nap, Kushida and Grandner agree, shouldn't last too long.
"You don't want to get into a deep stage of sleep," Grandner said. "If you've ever woken up from a nap that was too long, you know it because you feel miserable and groggy."
Napping too long during the day, Kushida added, can disrupt overall sleep patterns. "It's generally recommended to maximize sleep at night," he said.
Grandner said the exception might be if someone occasionally doesn't sleep enough at night and needs to recoup during the day.
"I call that the sleep replacement nap," he said. "College students do it a lot. They stay up at night, but then they nap a few hours during the day. That's not an ideal solution, but it's not terrible, either."
Lying down for a nap or laying your head on the desk might be a good time to reflect on the importance of sleep.
"We live in a culture that doesn't necessarily value sleep," Grandner said. "We need to stop talking about it as unproductive time, and to stop admiring people who brag about how little sleep they think they need.
"The scientific evidence is there," he said. "Sleep is a foundational part of our biology, like diet and physical activity. We need to take care of it."