Nine Godlewski
Newsweek
March 15, 2019

The annual event World Sleep Day is set to happen Friday, marking the end to Sleep Awareness Week, and it hopes to emphasize the importance of sleep to your personal health.

The day was created by sleep medicine professionals and researchers who wanted to create an event around “the importance of healthy sleep,” according to the event’s website.

Activities and events are planned worldwide, as they are each year for the Friday before the vernal equinox, marking the first day of spring. But at the core of World Sleep Day is the importance of sleep for the body and, equally as important, for the brain.

It’s easy to forget just how important sleep is to the brain and body. Missing out on a good night’s sleep can leave you feeling groggy, but you might not realize why you feel that way, or what your brain is missing out on by skipping those extra hours of shut-eye.

While a person sleeps, three essential processes go on in the brain that are necessary for it to perform at its best and remain healthy, Michael Merzenich, professor, co-founder and chief scientific officer of Posit Science, told Newsweek.

“The first thing that happens is that the brain basically is in a period of rejuvenation, just like the body. You can think of it as restoring its resources, and, of course, the body is also contributing to that,” Merzenich said.

“The second thing it’s up to is it’s taking out the garbage,” he added. This usually happens during rapid eye movement sleep, which is the dreaming segment of the night. REM sleep is usually when the most vivid dreaming occurs and happens about 90 minutes after sleep begins, according to the Cleveland Clinic. 

“Lots of unimportant things have happened in a day, the brain is judging them to be unimportant, and they basically increase the noisiness in the brain. And the brain has a really wonderful strategy for reducing that noisiness,” Merzenich said.

In addition to clearing out the brain to quiet excess background noise and to rejuvenate, the brain is working to index and process the important things that happened or were learned throughout the day. This happens during the deep sleep portion of the sleep cycle, Merzenich said.

One important aspect to be aware of, he continued, is that good sleep isn’t just about how long you sleep.

“You need to get enough sleep in time, but it’s also sleep quality. You need to go through this sleep cycling where the brain basically accomplishes these key things,” he explained.

Going without these key cycles and the important features of sleep can lead to more than a day full of yawning. A night here or there without enough sleep won’t cause any significant damage, but when it happens repeatedly, the brain is awash with that background noise Merzenich mentioned.

“It’s equivalent to accelerating the aging process in the brain, so it’s actually a very destructive thing to have in place in a continuous way. You don’t want to add to the noisiness of your brain,” Merzenich said. Luckily, sleep acts as an anti-noise element that can help things quiet down so the brain can perform at its peak.

Those who continually get poor sleep—either waking up frequently for no apparent reason or feeling that they never cycle through the different types of sleep—should consider going to a sleep clinic or seeing a doctor.