If you're drowsy in the afternoon, nap for 10 minutes, not half an hour
- High value
- Evidence B
- Saves time
- Free
- Takes minutes
- No willpower
In plain words
A 10-minute nap perks you up on the spot, and the effect lasts two and a half hours. A 5-minute nap does almost nothing. A 20-minute nap takes half an hour to start working. After a 30-minute nap, you wake up in a fog for a while, and in that period you perform worse than if you hadn't slept.
- Cost
-
Free. It takes 10 minutes, plus a place where you can lie down or rest your head on a desk.
- What you get
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After a night of too little sleep, a 10-minute nap immediately improved sleepiness, fatigue, energy and mental performance, and some of the benefit lasted past 155 minutes. A 5-minute nap had almost no benefit. The benefit of a 20-minute nap did not appear until after 35 minutes. After a 30-minute nap there was first a stretch of sleep inertia: performance was actually worse just after waking, and improved afterward.
- Notes
-
This is one lab study, with healthy young subjects. If you can't fall asleep, don't force it. No study supports whether lying with your eyes closed for 10 minutes does anything. Napping more than an hour is instead linked to higher mortality and coronary heart disease risk; see §2.37 (keep naps to half an hour).
- Evidence grade
- B : Supported by research but without a precise number, or based on small or single studies.
- Sources
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- Brooks & Lack (2006). A brief afternoon nap following nocturnal sleep restriction: Which nap duration is most recuperative? Sleep. https://doi.org/10.1093/sleep/29.6.831
Mentioned in
Translated from the Chinese original. Original book, section 3, tip 11. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer