The power nap – why short beats long

You slept badly, it's early afternoon and your eyelids are heavy. Lying down for a bit is tempting, but you remember last time: you woke up an hour later, confused and heavier-headed than before.

The nap isn't the problem. The length is.

What happens when you sleep during the day

Sleep runs in cycles. First light sleep, then progressively deeper, before the brain turns back up towards the surface and dream sleep takes over. A full cycle takes a good while.

If you wake during light sleep, it's easy to get going. If you wake in the middle of deep sleep, the opposite happens: the brain is still set to night, thoughts move slowly, and it can take a long time before you feel clear. It's called sleep inertia, and it's why a long nap often feels like a mistake afterwards.

A short nap never gets down into deep sleep. You get the rest and the boost in alertness, but skip the hangover.

What the research shows

An Australian study (Brooks & Lack, Sleep, 2006) compared naps of different lengths in people who had been short on sleep the night before. Afterwards, their alertness and sharpness were measured, right after waking and for several hours on.

The short nap of around ten minutes gave the best results. Participants were clearly more alert straight away, without first having to shake off the sleep, and the effect lasted for a good part of the afternoon.

The longer naps also brought an improvement, but only after a period of sleep inertia during which participants performed worse than before they lay down. The very shortest naps, just a few minutes, had considerably less effect.

The conclusion is simple: there's a sweet spot, and it sits around ten minutes.

What to do

1. Set an alarm. Allow a few minutes to fall asleep, so the sleep itself lands at around ten minutes. If you don't wake on your own, get up when the alarm goes off, even if you feel like more.
2. Take it early in the afternoon. Your body has a natural dip after lunch, and that's where a nap fits best. Later in the day it risks stealing from your night's sleep.
3. Make it easy to drop off. Dark room or an eye mask, quiet or headphones, reclined in a chair or on a sofa. You don't need a bed – it's actually better not to have one.
4. Don't aim for deep sleep. Even just lying with your eyes closed for ten minutes gives you rest. The pressure to fall asleep only makes it harder.

A habit, not an emergency fix

Naps work best as a complement, not a replacement for sleeping at night. If you're regularly short on sleep, that's where the real problem sits.

But as a tool for a sluggish afternoon, it's hard to beat. Log in the app when you take one, and how you feel an hour later. After a few weeks you'll know exactly how long your nap should be.