In the 1990s, NASA gave long-haul pilots a 40-minute window to nap in the cockpit seat while colleagues flew the plane. On average they slept about 26 minutes, and afterwards their performance on alertness tests improved by 34%. That's the promise of a good power nap: a short, well-timed sleep of about 10–20 minutes in the early afternoon can sharpen alertness for a couple of hours without leaving you groggy or wrecking your night.
Key takeaways
- The sweet spot for a power nap is 10–20 minutes, short enough to avoid deep sleep and the grogginess that follows it.
- In a well-known Australian study, a 10-minute nap improved alertness almost immediately, with benefits lasting over two hours.
- Nap between roughly 1pm and 3pm, when your body clock naturally dips, and not late in the day.
- A "coffee nap", caffeine just before a 15–20 minute nap, can work better than either alone.
- If you have insomnia or regularly need long daytime naps, that's a sign to look at your night-time sleep or see a doctor.
Why does a power nap work?
Two systems control how sleepy you feel. One is sleep pressure, a chemical build-up (largely adenosine) that increases the longer you're awake. The other is your circadian rhythm, your internal 24-hour clock. In the early afternoon, the clock produces a natural dip in alertness. This happens whether or not you've eaten, which is why the post-lunch slump isn't just about the nasi campur (though a heavy lunch doesn't help; see our guide to the 3pm slump).
A short nap relieves some of that sleep pressure. You spend the time in the lighter stages of sleep, which appear to be enough to reset alertness and attention without plunging you into deep sleep.
How long should a power nap be?
This is the question that matters most, and the research is fairly clear. In a 2006 study in the journal Sleep, Amber Brooks and Leon Lack at Flinders University tested naps of 5, 10, 20 and 30 minutes in people who had slept less than usual the night before. The 5-minute nap did little. The 10-minute nap produced immediate improvements in alertness and performance that lasted about two and a half hours. The 20- and 30-minute naps also helped, but only after a period of grogginess.
That grogginess is called sleep inertia. It happens when you wake from deep (slow-wave) sleep, and it can last anywhere from a few minutes to half an hour. The longer you nap, the more likely you are to hit deep sleep.
| Nap length | What happens | Best for | Downside |
|---|---|---|---|
| Under 5 min | Barely any sleep | Not much | Little measurable benefit |
| 10–20 min | Light sleep only | Quick alertness boost at work or before driving | Very little; the classic power nap |
| 30–45 min | May enter deep sleep | Occasional use when very sleep-deprived | Grogginess on waking |
| 60 min | Deep sleep likely | Some types of memory consolidation | Strong sleep inertia; may affect night sleep |
| About 90 min | A full sleep cycle, including REM | Recovery after a very short night; shift workers | Takes a big chunk of the day; can delay bedtime |
A caveat on the 90-minute nap: some studies, including work by Sara Mednick, found that longer naps containing both deep and REM sleep can improve certain kinds of learning. But for everyday energy, short beats long.
When is the best time to nap?
For most people with a typical daytime schedule, the best window is roughly 1pm to 3pm, which lines up with the circadian dip. Mayo Clinic advises keeping naps before 3pm, because later naps can make it harder to fall asleep at night.
If you work shifts, the rules shift too. A nap before a night shift can help reduce sleepiness during it, and a short nap during a break can improve safety on the job.
What's a coffee nap, and does it work?
It sounds contradictory, but it's one of the better-supported tricks. Caffeine takes roughly 20 minutes to start having an effect. Drink a coffee (or a kopi-o kosong) quickly, then nap immediately for 15–20 minutes. You wake just as the caffeine arrives, and because the nap has cleared some adenosine, caffeine has less competition at its receptors.
In driving-simulator research by Jim Horne and Louise Reyner at Loughborough University, sleepy drivers who had caffeine followed by a short nap had fewer lane drifts and felt less sleepy than those who had caffeine or a nap alone. The obvious catch: this is an early-afternoon trick. Caffeine has a half-life of around five hours, so a late coffee nap can cost you sleep that night. Our article on caffeine timing explains how late is too late.
How to take the perfect power nap
- Set an alarm for 20–25 minutes. That allows about five minutes to drift off and 15–20 minutes of sleep.
- Make it dark-ish and quiet. An eye mask and earplugs turn a meeting room, car passenger seat or desk into a workable nap spot.
- Get comfortable, not too comfortable. Reclining is ideal; lying fully in bed makes oversleeping more likely.
- Keep it cool. Aircon is a rare advantage here.
- Don't stress about actually sleeping. Even quiet rest with eyes closed can help you feel more refreshed.
- Get up straight away. Splash water on your face, step into daylight and move for a minute to shake off any inertia.
- Keep it consistent. A regular nap time is easier for your body than random ones.
Is napping good for your health?
The research is mixed and hard to untangle. A large Greek study published in 2007 reported that people who took regular midday siestas had lower coronary death rates. On the other hand, several meta-analyses have linked frequent long naps (over an hour) to higher risks of heart disease and death.
The most likely explanation is that long, frequent daytime sleep is often a sign of something else: poor night-time sleep, sleep apnoea, depression or an underlying illness. Short, planned naps appear to be fine, and helpful for alertness. Needing long naps every day is worth investigating.
Who should skip naps?
- People with insomnia: naps reduce the sleep pressure you need to fall asleep at night. Standard insomnia treatment usually advises avoiding them.
- People who feel worse after napping, even when short.
- Anyone using naps to cover a chronic sleep shortfall. A nap is a patch, not a replacement for seven to nine hours at night. If that's you, start with our guide to winning back your nights.
And if you're ever drowsy behind the wheel, pull over somewhere safe and take a 15–20 minute nap. It's far safer than pushing on with the windows down and the radio up.
This article is general information, not medical advice. If you experience excessive daytime sleepiness, loud snoring, pauses in breathing during sleep or long-term insomnia, please see a doctor, as these can signal a sleep disorder that needs proper assessment.
Frequently asked questions
How long should a power nap be?
Aim for 10–20 minutes of sleep, which usually means setting an alarm for 20–25 minutes. Research suggests this length boosts alertness quickly without the grogginess that comes from waking up out of deep sleep.
Why do I feel worse after a nap?
That grogginess is called sleep inertia, and it usually happens when you wake from deep sleep during a longer nap. Keeping naps under about 20 minutes, and getting light and movement straight after, helps avoid it.
What time of day is best for a power nap?
Between about 1pm and 3pm for most people, when the body clock naturally dips. Napping later in the afternoon or evening can make it harder to fall asleep at night.
Does a coffee nap really work?
Studies suggest drinking caffeine immediately before a short nap can reduce sleepiness more than either caffeine or a nap alone, because the caffeine starts working as you wake. Use it early in the day so it doesn't disrupt your night-time sleep.
Is it bad to nap every day?
A short daily nap is fine for many people and common in many cultures. But if you regularly need long naps to function, it may mean you're not getting enough good-quality sleep at night, and it's worth talking to a doctor.
