Nap calculator
Pick the kind of nap you need. The calculator tells you what each one does, what it’s best for, and exactly when to set your alarm.
The three useful nap lengths
Most nap advice is wrong because it treats “napping” as one thing. There are really three distinct interventions, and the wrong one at the wrong time is worse than no nap at all (Mednick et al., 2006, compared nap durations and showed each produces a different cognitive profile).
20 minutes — the power nap
Stays in light NREM. You don’t enter deep sleep, so you wake fast and feel sharper for the next 2–3 hours. The classic afternoon-slump fix. Reliable, low-risk, no grogginess.
60 minutes — the recovery nap
Includes some slow-wave sleep, which is where consolidation of declarative memory and physical recovery happen. The cost is sleep inertia on waking — set aside 15–20 minutes to come back online. Worth it after a bad night or before a long evening.
90 minutes — the full cycle
One complete light → deep → REM cycle, ending back in light sleep. You wake feeling mostly normal, with the cognitive benefits of REM (creative problem-solving, emotional processing). Best when you have the time and are recovering from real sleep loss.
The 30-minute trap
Avoid naps in the 25–60 minute range. You enter deep sleep but haven’t completed a cycle, so the alarm catches you at the worst possible moment. The grogginess can last longer than the nap itself.
Caffeine and naps
The "coffee nap" — ~100 mg of caffeine right before lying down — has small but real RCT evidence behind it. Caffeine takes about 20 minutes to peak, which lines up with a power nap. The adenosine your brain accumulated in the morning gets cleared during the nap; the caffeine then blocks new adenosine from binding. Effects compound briefly. Don’t use this every day.
Frequently asked questions
How long should I nap?
Three answers, depending on what you need. A 20-minute power nap gives a quick alertness boost without entering deep sleep — best for an afternoon slump or before driving. A 60-minute recovery nap includes some slow-wave sleep — best after a poor night, with the trade-off that you’ll have 15–20 minutes of grogginess on waking. A 90-minute full-cycle nap takes you through one complete cycle and you wake during light sleep — best on weekends or jet lag recovery.
Why is a 30-minute nap worse than a 20-minute one?
At about 25–30 minutes you start entering slow-wave (deep) sleep but haven’t completed a cycle. Waking in deep sleep produces strong sleep inertia — the dull, slow, groggy feeling that takes 30+ minutes to clear. Either keep the nap under 25 minutes, or commit to a full 90 minutes so you wake at a cycle boundary.
Is it bad to nap every day?
No, if it’s short (under 30 minutes) and earlier than 3 PM. Regular short naps don’t disrupt night sleep and are associated with better cognitive function in older adults. Long or late naps can cut into the sleep pressure you need to fall asleep at night.
Should I drink coffee before a nap?
The "coffee nap" — drinking ~100 mg caffeine immediately before a 20-minute nap — has small RCT evidence supporting it. The caffeine takes ~20 minutes to peak, so it kicks in just as you wake. Anecdotally effective; do not chain.
When is the best time to nap?
Between 1 PM and 3 PM for most people. That’s when the circadian alertness signal naturally dips (the "post-lunch dip" is real but happens with or without lunch). After 4 PM, napping starts eating into the sleep pressure you need for the next night.
How long should a nap be for a 1-year-old?
Most 1-year-olds need about 2–3 hours of daytime sleep, often split into one morning nap (under 1 hour) and one afternoon nap (1.5–2 hours), gradually consolidating to a single afternoon nap by 18 months. This calculator is for adults; for child sleep schedules consult pediatric sleep guidelines.