Can a really good nap undo a bad night of sleep?

Maybe you stayed up too late scrolling TikTok or tossed and turned because of anxious thoughts. Now, you are wondering if a quick lunchtime nap will give you the energy boost you need to power through the rest of the day and potentially regain the health benefits of a full night’s sleep you may have lost.

If I get less than the recommended seven or eight hours of sleep every night, will a midday nap make up for that loss?

It is important to understand that while a midday nap will probably replenish your energy enough to get you through your day, it will not necessarily negate the health risks that may come with insufficient sleep at night, said Dr Rebecca Spencer, a sleep science researcher at the University of Massachusetts Amherst.

The health benefits of 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 do not get the recommended seven hours or more of sleep every night. 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, Dr Spencer said, but also the quality of that sleep, which is determined by how much time you spend in its different stages.

When one sleeps throughout the night, one passes through several sleep cycles of about 90 minutes. Each comprises 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 (REM) is the last stage of the sleep cycle. It is not as deep as the third stage, but it is when you are most likely to dream and is thought to be associated with learning, storing memories and regulating mood.

It is normal to have a poor night of sleep every now and then, said Dr Molly Atwood, a clinical psychologist and behavioural sleep medicine researcher at The Johns Hopkins School of Medicine. But if you do not consistently pass through all of these stages every night, she said, that can lead to a range of health conditions.

And naps cannot compensate for that, Dr 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 do not add up in the same way.

Short naps of less than 90 minutes typically include only the lighter phases of sleep, she added, 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 mathematics questions than those who wake from REM sleep.

The upside of napping

But there are some instances where short naps can be helpful, Dr Atwood said. “When you haven’t had a great night of sleep, napping can help improve things like reaction time and memory if you need to be working,” she added.

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, she said.

Naps can also be particularly important for helping to keep those who do not always work daytime schedules – such as airline pilots, commercial drivers, physicians or other shift workers – alert and sharp. Similarly, they can help older adults if age-related changes, such as needing to use the bathroom at night, interrupt their sleep, Dr Atwood said.

If you find yourself in need of a nap, she said, keep it short – no more than 30 minutes – so it does not interfere with your next night of sleep. It is 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 are chronically tired or have trouble getting through the day without a nap, Dr Atwood said to consider 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, she added. 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. NYTIMES

This article was originally published in The Straits Times.