Use the 30-90 Rule to Take the Perfect Nap

Source Article: https://www.inc.com/jessica-stillman/use-30-90-rule-to-take-perfect-nap.html

A little bit of science can help you wake up feeling alert and refreshed rather than groggy and grumpy.

By Jessica Stillman , Contributor, Inc.com

Naps, study after study tells us, are great for your memory , cognitive performance , physical health , and all-around productivity. So why, when you take one, do you often wake up feeling logy and listless? If all the scientists are right and naps are great for you , why do they often leave so many of us feeling bad?

The answer to this question might surprise you -- taking a good nap is actually harder than it first appears.

That's counterintuitive as we've all been napping successfully since the day we were born. What could be less complicated than rolling out a mat on the floor or your kindergarten classroom and snuggling in? But while it's true that napping comes naturally to humans, experts insist that getting an actually refreshing nap as a busy adult requires a basic understanding of one essential principle -- the 30-90 rule.

It's all about our sleep cycles.

I was reminded of this fact recently when I came across an article from our sister site Fast Company with a fun premise -- what can truckers, who often have to snatch what shut-eye they can at odd hours, teach us about how to get better sleep? The whole thing is worth a read, but one tidbit from Dean Croke, a freight industry insider who teaches sleep science classes to truckers and shift workers, stood out.

Croke explains to writer Stephanie Vozza that human sleep isn't one monolithic experience. When we doze off, our brains cycle through different sleep phases in regular blocks of about 90 minutes.

"If we were to wire our brains with scalp electrodes, like they do in sleep studies, you would see different electrical pulses between the neurons in the brain," Croke says. "They translate to different levels of sleep."

For about the first 30 minutes after lying down you're likely in a phase of light sleep. Eventually you enter a phase of deeper sleep which lasts between 30 and 75 minutes. Finally, before waking you experience a period of REM sleep where you do your most intense dreaming. Each phase has different functions, Croke tells Vozza.

"Deep sleep deals with the fatigue. REM sleep deals with memory and mood, archiving the memories and flushing out the brain of the things it doesn't need," he says.

That's not just fascinating biological trivia. Knowledge of sleep cycles can also help you plan a nap that leaves you refreshed and clear-headed rather than groggy and grumpy. The key, according to Croke, is to avoid trying to wake up from deep sleep. This means you should probably aim to sleep for 30 minutes or less or give yourself at least 90 minutes for your nap -- aka the 30-90 rule.

NASA agrees with the truckers.

Croke comes at this rule from an unusual background, but he's far from the only expert who insists that naps should either be short or long and nothing in between. NASA, for instance, tested the ideal nap length to boost cognitive performance and found a snooze of 26 minutes was ideal, boosting performance on the job by 34 percent. That's an oddly precise finding but it basically boils down to the 30 in the 30-90 rule.

1. If your aim is to refresh your brain and boost memory and concentration, a short nap is best.

2. If you need to whittle away at a more serious sleep debt because you haven't been getting the recommended seven to eight hours a night, then science agrees with Croke that you should aim to complete a full sleep cycle.

As a handy Boston Globe summary of the science of sleep puts it:
"Naps of 90 to 120 minutes usually comprise all stages, including REM and deep slow-wave sleep, which helps to clear your mind, improve memory recall, and recoup lost sleep." As an added bonus, waking from REM sleep leaves you feeling much perkier than trying to drag yourself out of deep sleep.

So if you find yourself dragging after your afternoon snoozes, the problem is probably not your nap, but your nap technique. For better results heed the science and always set your alarm for either 30 minutes or less or 90 minutes or more.