Croke's 90-30 rule
Several studies have shown that naps are beneficial for your memory, cognitive ability, physical health, and overall productivity. Moreover, it that taking naps helps workers function better (and busy entrepreneurs). Why do you frequently wake up after taking one feeling drowsy and listless? If all the scientists are correct and naps are so beneficial for you, why do so many of us find that they frequently make us feel bad?
But to be precise, taking a good nap is harder than it first appears.
We’ve all been napping effectively from the day we were born, so it seems counterintuitive. What could be simpler than spreading a mat on the floor in your kindergarten class and snuggling in? While it’s true that people naturally nap, experts contend that taking a rejuvenating nap as a busy adult necessitates a fundamental comprehension of one crucial principle — the 30-90 rule.
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 whatever shuteye they can at odd hours, teach us about how to get better sleep? The whole article 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’s 90-30 rule
According to Dean Croke, 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.
Crokes explains to writer Stephanie Vozza, he said, “If we were to wire our brains with scalp electrodes as they do in sleep studies, you would see different electrical pulses between the neurons in the brain.”
“They translate to different levels of sleep,” he said.
For about the first 30 minutes after lying down, you are probably in the light sleep stage. Finally, you enter a deep sleep phase lasting 30-75 minutes. Before you wake up, you will experience the phase of REM sleep when you have your most intense dreams. Each phase has different functions, he further said.
“Deep sleep deals with fatigue. REM sleep deals with memory and mood, archiving the memories and flushing out the brain of the things it doesn’t need.”
These aren’t just fascinating biological trifles. Knowing your sleep cycle can also help you plan naps that leave you feeling refreshed and clear-headed, rather than left limp and grumpy. According to Croke, the key is to avoid waking up from a deep sleep. This means that he should sleep no more than 30 minutes or at least 90 minutes. Here is his 30-90 rule.
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NASA agrees to Croke’s 30-90 Rule
Croke has a unique perspective on this concept, but he’s far from the only expert who insists that naps should either be short or long and nothing in between. For instance, NASA evaluated the best nap duration to improve cognitive performance and discovered a 26-minute nap was perfect, improving performance at work by 34%. That’s an eerily accurate conclusion, but it basically comes down to the 30-90 rule.
A little nap is ideal if your goal is to revive your brain and improve memory and attention. Science agrees with Croke that you should attempt to finish a full sleep cycle if you need to reduce a more serious sleep debt since you haven’t been obtaining the required seven to eight hours every night.
“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,” according to the reports of Boston Globe summary of the science of sleep.
So, if you find yourself dragging after your afternoon snoozes, the problem is probably not your nap, but your nap technique. Always set your alarm for 30 minutes or less or 90 minutes or more to achieve the best results.
