If you can't sleep after a nap, it's usually because the nap was too long or too late and used up the sleep pressure you need to fall asleep at night. Tonight, go to bed when you actually feel sleepy, not before, and keep tomorrow's wake-up time the same. Going forward, keep naps to 10 to 20 minutes and finish them at least 7 hours before bed, or 8 hours for a long nap.
Free toolNap CalculatorWhen to set your alarm for a power nap or a full-cycle nap.Why can't I sleep after a nap?
The main reason is sleep pressure. From the moment you wake up, a drive to sleep slowly builds in your brain, a bit like air filling a balloon. By bedtime, the balloon is full and you drift off easily. Sleep lets the air out.
A nap lets some of that air out early. A short nap in the early afternoon releases a little, and there's time for it to build back up before bed. A long nap, or one late in the day, releases a lot, and there isn't enough time to refill it. You lie in bed feeling wide awake, even though you know you should be tired.
Sleep researchers describe this with the two-process model: sleep pressure builds with time awake and falls during sleep, while your body clock sets the times of day you feel most alert and most sleepy. You fall asleep most easily when both line up. A late nap throws that off.
Why a long nap makes it worse
Length matters as much as timing. In a short nap you mostly stay in light sleep. In a longer nap you're more likely to reach deep sleep, which releases much more of your sleep pressure.
Research shows you don't need much. In one study, a nap of just 10 minutes after a short night improved alertness and performance for up to about 2.5 hours. If you get the benefit from 10 to 20 minutes, a 2-hour nap mostly costs you sleep later. See is a 90-minute nap too long for when a longer nap does make sense.
Latest time to finish a nap for your bedtime
Use this as a rule of thumb, not a hard rule. Everyone's sleep pressure builds at a slightly different rate. The "lie down by" times assume 10 minutes to fall asleep, the default in the nap calculator.
| Your bedtime | 20-min nap: lie down by | 20-min nap: be up by | 90-min nap: lie down by | 90-min nap: be up by |
|---|---|---|---|---|
| 9:00 PM | 1:30 PM | 2:00 PM | 11:20 AM | 1:00 PM |
| 9:30 PM | 2:00 PM | 2:30 PM | 11:50 AM | 1:30 PM |
| 10:00 PM | 2:30 PM | 3:00 PM | 12:20 PM | 2:00 PM |
| 10:30 PM | 3:00 PM | 3:30 PM | 12:50 PM | 2:30 PM |
| 11:00 PM | 3:30 PM | 4:00 PM | 1:20 PM | 3:00 PM |
| 11:30 PM | 4:00 PM | 4:30 PM | 1:50 PM | 3:30 PM |
| 12:00 AM | 4:30 PM | 5:00 PM | 2:20 PM | 4:00 PM |
| 1:00 AM | 5:30 PM | 6:00 PM | 3:20 PM | 5:00 PM |
The rule behind the table: finish a short nap at least 7 hours before bed and a 90-minute nap at least 8 hours before bed. If you already struggle to fall asleep at night, leave even more room, or skip naps for a week or two.
How to fall asleep after taking a nap
If you napped too long or too late today, here's how to get through tonight:
- Don't go to bed early to "make up" for it. Lying in bed wide awake tends to make it worse. Wait until you feel genuinely sleepy, even if that's later than usual.
- Wind down in dim light. Lower the lights and screens for the last hour, and do something calm, like reading or a shower.
- Skip more caffeine. Even an afternoon coffee can linger at bedtime. Check with the caffeine calculator.
- Don't lie there for ages. If you're awake for what feels like 20 minutes or so, get up, do something quiet in low light, and return when you're drowsy. More in lying in bed awake.
- Get up at your usual time tomorrow. Sleeping in resets the problem. A normal wake-up time rebuilds sleep pressure for the next night.
- Don't nap tomorrow, or keep it to 10 to 20 minutes before mid-afternoon.
A little physical activity in the afternoon or early evening can also help you feel more ready for sleep, as long as it isn't intense and right before bed.
Can't sleep after a nap every day?
If this keeps happening, change the nap, not your bedtime. Most people do well with one of these setups:
- A short early nap: 10 to 20 minutes in the early afternoon. The best time to take a nap is usually 6 to 8 hours after you wake up.
- No nap at all: if you're sleeping 7 to 9 hours a night, you may not need one.
- A later bedtime to match: if you nap because you're a natural night owl, it may be more realistic to shift your whole schedule than to fight it. Use the nap calculator to set exact alarm times.
And if you need a long nap every day because you're exhausted, look at your nights. Short night sleep is the most common reason for heavy afternoon napping. The sleep calculator can find a bedtime that fits your alarm.
When to see a doctor
Occasional trouble sleeping after a nap is normal. See a doctor if you're sleeping 7 to 9 hours a night and still need long naps to function, if you fall asleep during the day without meaning to, or if you have insomnia most nights for several weeks. Loud snoring, gasping or pauses in breathing at night can be signs of sleep apnea.