If you’re skidding into 2021 feeling like Hunter S. Thompson after a three-day coke binge, you might be thinking, I may as well just nap until the new year. But while that sounds relaxing in theory, napping for that long would certainly do far more harm than good.
In hopes of determining the best length for a nap, sleep scientists have performed all sorts of studies, and their conclusions are pretty straightforward: Napping five minutes or less is too short of a time for your body to move through the various sleep stages that produce a notable benefit. Napping for 30 minutes or longer, on the other hand, gives your body enough time to enter deep, reinvigorating (slow-wave) sleep. However — and this is a big however — napping for too long or waking up from slow-wave sleep can leave you feeling groggy, a phenomenon called “sleep inertia,” for up to an hour, which, of course, defeats the purpose of napping altogether.
Going by these findings, the best length for a nap in most cases — one long enough to be rejuvenating but short enough to prevent grogginess — is anywhere between 10 and 20 minutes. (For more advice on taking a proper nap in that short of a time, check out our napping guide for people who suck at napping.)
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Now, there are a couple exceptions. When you’re sick, for instance, your body requires more sleep than usual, and therefore, longer naps may be needed. Children and teenagers also need more sleep in general than adults, and therefore may require longer naps — one 2019 study, for example, found that the ideal nap length for teens is around 30 to 60 minutes.
If you really want to take a longer nap than between 10 and 20 minutes, you still can. In fact, you may even benefit from a longer nap if your body needs it. Sleeping for 90 minutes or more puts your body through the whole sleep cycle, which should help your body and mind feel better in the long-term. Just make sure you have nothing important to do directly after your lengthy nap, because you very well may end up feeling like you were born into a whole new world and need some time to figure things out for yourself.
So assess your needs and nap appropriately. If you do end up napping until 2021, well, good for you, man.