Naps Done Right: How Long, When and Who Should Skip Them

The benefits

Short naps can improve alertness, reaction time and mood, particularly when you are short on sleep. NASA research on long-haul pilots in the 1990s found that a planned cockpit rest period, in which pilots slept on average about 26 minutes, improved their performance and alertness compared with pilots who did not nap.

The ideal length

A nap of about 10 to 20 minutes usually keeps you in light sleep, so you wake feeling refreshed. Longer naps are more likely to reach deep sleep, and waking from deep sleep can cause sleep inertia: grogginess that can last 30 minutes or more. A nap of about 90 minutes allows a full sleep cycle and may be useful before a night of planned sleep loss, but it takes a bigger bite out of night-time sleep pressure.

The best time

Early afternoon, roughly 1pm to 3pm for someone on a typical day schedule, lines up with a natural dip in alertness. Napping in the late afternoon or evening reduces your sleep drive for the night and can make it harder to fall asleep.

How to nap well

• Set an alarm for about 20 to 30 minutes, allowing time to fall asleep.
• Lie down somewhere dark, quiet and cool, or use an eye mask and earplugs.
• Try a 'caffeine nap': some people drink a coffee immediately before a 20 minute nap, so the caffeine starts working as they wake. Avoid this late in the day.
• Give yourself a few minutes after waking before driving or doing anything safety critical.

Napping for shift workers

Naps are a key tool for night shift workers. A nap of 1 to 2 hours in the afternoon or early evening before a night shift can reduce sleepiness during the shift. Where workplace policy allows, a short nap of 20 to 30 minutes during a break can improve alertness. A nap before driving home after a night shift can also reduce the risk of drowsy driving.

Who should skip naps

If you have insomnia, daytime naps can reduce the sleep drive you need at night, and CBT-I programs usually advise avoiding them, at least early in treatment. If you suddenly need naps you never needed before, or fall asleep unintentionally during the day despite enough night-time sleep, see a doctor: excessive daytime sleepiness can be a sign of sleep apnea, narcolepsy, depression, medication effects or other conditions.