A 20-minute nap can boost alertness, memory, and mood — but a 90-minute nap can leave you groggy and hurt your night sleep. The ideal nap is about 20 minutes, taken before 3 p.m., in a cool, quiet, dark place. Longer naps risk waking from deep sleep, and regular long naps are linked to health risks in some studies. This guide explains the evidence, the best nap habits, and when daytime sleepiness means you should see a doctor. Reviewed 2026.
What a nap can do
A nap is a short period of sleep during the day. For many adults, naps help maintain alertness or overcome daytime fatigue. The evidence supports several benefits:
- Better alertness and performance — a short nap can improve memory, logical reasoning, and the ability to complete complex tasks.
- Recovery after poor sleep — after a night of insufficient sleep, a nap can counteract daytime drowsiness.
- Shift-work support — naps are particularly helpful for shift workers who must be alert at irregular times.
- Possible heart benefits — one observational study found napping one or two times a week was associated with lower cardiovascular risk, though more research is needed.
How long should a nap be?
The best nap length for adults is about 20 minutes, and no longer than 30 minutes. A 20-minute nap keeps you in light sleep, so you wake refreshed. Naps longer than 30 minutes can take you into deep sleep — and waking from deep sleep causes grogginess that can actually worsen sleepiness.
In some cases, a longer nap of about 90 minutes can be beneficial — it lets the body complete a full sleep cycle. This is mainly useful for emergency workers and shift workers fighting fatigue. For most people, a 90-minute nap is too much.
When to nap
Experts recommend napping eight or more hours before bedtime — for most people, that means before 3 p.m. Napping too late in the day can interfere with nighttime sleep.
Many people feel sleepy in the early afternoon — the "post-lunch dip." This is linked to your circadian rhythm, not just lunch. A brief nap around this time can reduce afternoon sleepiness without hurting night sleep.
When napping is a problem
Napping can backfire:
- Long naps (over 30 minutes) — grogginess, and some studies link regular long naps to higher blood pressure, type 2 diabetes risk, and fatty liver in older adults.
- Late naps — interfere with nighttime sleep, especially in older adults.
- Naps as a substitute for night sleep — depending on naps instead of consistent nighttime sleep can contribute to fragmented sleep or insomnia.
If you are not a regular napper and function well without one, you do not need to start. Napping is a tool, not a requirement.
Red flags: when to see a doctor
- you fall asleep unexpectedly or at unwanted times — this is different from napping and may signal excessive daytime sleepiness or narcolepsy
- you are unable to stay awake during normal daytime hours despite enough night sleep
- you have low mood, weight or appetite changes, or loss of interest in activities you usually enjoy — excessive napping can be a symptom of anxiety or depression
- you regularly need naps because you cannot get enough sleep at night — that is a sleep problem to investigate, not a habit to accept
How to take a good nap
- Set an alarm for 20 minutes — and get up when it sounds. Do not hit snooze; that risks entering deeper sleep.
- Choose a cool, quiet, dark place — blackout curtains, earplugs, or an eye mask help.
- Nap before 3 p.m. — late naps steal from night sleep.
- Consider a caffeine nap — caffeine takes about 30 minutes to kick in, so coffee right before a short nap can boost alertness after waking.
- Move after waking — stretch or walk to shake off post-nap sleepiness.
What does not help
- Napping longer than 30 minutes — deep-sleep grogginess and, for some, health risks.
- Napping after 3 p.m. — steals from night sleep.
- Using naps to replace night sleep — fragmented sleep and insomnia risk.
- Ignoring excessive daytime sleepiness — it can signal a treatable sleep disorder.
Sources
- Sleep Foundation — Napping: Benefits and Tips: sleepfoundation.org/napping (updated May 2026, accessed September 2026)
- Sleep Medicine Reviews (2024) — To nap or not? Evidence from a meta-analysis of cohort studies: sciencedirect.com
- CDC — Sleep and shift work: cdc.gov
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