The health benefits of a good sleep
According to 2020 survey data from the Centers for Disease Control and Prevention, more than one-third of adults in the United States don’t get the recommended seven hours or more of sleep every night. And that lack of sleep, experts say, is associated with a range of increased health risks, including for obesity, high blood pressure, diabetes, coronary heart disease, stroke and mental distress.
Not only is the length of time you sleep important for health, Spencer said, but also the quality of that sleep, which is determined by how much time you spend in its different stages.
When we sleep throughout the night, we pass through several “sleep cycles” of about 90 minutes. Each is composed of four stages: the first two are considered light sleep, where your muscles relax, your body temperature drops, and your heart rate and breathing slow as you doze off.
The third stage, known as deep sleep, is when your eyes and muscles fully relax and your body does the important work of repairing and building bone, muscle and other tissues, as well as strengthening the immune system and consolidating and processing memories. Rapid eye movement (or REM) is the last stage of the sleep cycle. It is not as deep as the third stage, but it’s when you’re most likely to dream and is thought to be associated with learning, storing memories and regulating mood.
It’s normal to have a poor night of sleep every now and then, said Molly Atwood, a clinical psychologist and behavioural sleep medicine researcher at Johns Hopkins Medicine. But if you don’t consistently pass through all of these stages every night, that can lead to a range of health conditions.
Naps can’t compensate for that, Spencer said.
Even though a few hours of sleep at night and a nap during the day might add up to six or more hours total, she said, the health benefits don’t add up in the same way. Short naps of less than 90 minutes typically only include the lighter phases of sleep, not the deep, restorative sleep that you usually get throughout the night.
And while naps of more than 90 minutes might include some beneficial deep sleep, they will be more likely than shorter naps to leave you feeling groggy and potentially less sharp. Some limited evidence, for instance, has found that those who wake from the deepest phase of the sleep cycle are more likely to make mistakes on maths questions than those who wake from REM sleep.
The upsides of napping
But there are some instances where short naps can be helpful, Atwood said. “When you haven’t gotten a great night of sleep, napping can really help improve things like reaction time and memory if you need to be working.”
If you usually work during the day, for instance, a 20- to 30-minute nap can restore alertness without leaving you groggy or disrupting your sleep the next night, Atwood said.
Naps can also be particularly important for helping to keep those who don’t always work daytime schedules — such as airline pilots, commercial drivers, physicians or other shift workers — alert and sharp. And similarly, they can help older adults if age-related changes such as needing to use the bathroom at night interrupt their sleep, Atwood said.
If you find yourself in need of a nap, Atwood said, keep it short — no more than 30 minutes — so it doesn’t interfere with your next night of sleep. It’s best to snooze in the afternoons, “when we have a natural dip in alertness and tend to feel sleepy”, she added. That makes it easier to fall asleep quickly.
But if you’re chronically tired or having trouble getting through the day without a nap, Atwood advises seeking the help of a behavioural sleep specialist.
“People tend to suffer for a while, and then they go to their primary care physician and get some medication,” she said. But seeing a sleep specialist is a better long-term solution than relying on medication. These professionals, who are trained in sleep psychology, can offer certain exercises or strategies like cognitive behavioural therapy that can help you get the rest you need.
This article originally appeared in The New York Times.
Written by: Jyoti Madhusoodanan
©2023 THE NEW YORK TIMES
