Power nap sounds.
The hard part of a nap is not falling asleep — it is waking up on the right side of the line. Sleep past about twenty-five minutes and you drop into slow-wave sleep, where being woken produces the heavy, useless feeling researchers call sleep inertia. This page gives you a theta-band bed that fades out and stops at twenty minutes, so the audio ends before that line rather than after it.
The audio is not an alarm. It fades out and stops after twenty minutes, which is a cue, not a wake-up — if you actually need to be somewhere, set a real alarm as well. Binaural mode needs headphones; if you are napping on a sofa without them, open the isochronic version instead, which works on a speaker. Open this in the full generator →
Why twenty minutes and not forty-five.
Because a short nap borrows from light sleep, and a long one interrupts deep sleep. Sleep is not uniform: in the first half hour you pass through light stages you can be pulled out of easily, and after roughly twenty-five to thirty minutes you begin entering slow-wave sleep, which is the stage that produces grogginess if you are woken mid-way through it.
The clearest experimental comparison is Brooks and Lack (2006), published in Sleep, which put the same people through 5-, 10-, 20- and 30-minute afternoon naps after a restricted night. The 10-minute nap produced the most useful pattern: benefits to alertness and performance that appeared almost immediately and lasted a couple of hours. The 30-minute nap did help, but only after a period of impairment on waking — the inertia showing up exactly where the sleep stages predict it should.
| Nap length | What you get | The catch |
|---|---|---|
| 5–10 min | Alertness back quickly, almost no grogginess | Little effect if you are heavily sleep-deprived |
| 20 min | The usual recommendation; a real recovery without crossing into slow-wave sleep | Some people need most of it just to fall asleep |
| 30–45 min | More recovery, eventually | You are likely woken out of slow-wave sleep; expect grogginess first |
| 90 min | A full cycle, ending back in light sleep | Rarely practical, and it will move your night sleep |
So twenty is the compromise, not the optimum: long enough to be worth doing, short enough that you are still in light sleep when it ends. If you are consistently taking more than ten minutes to drop off, count that time — a “twenty-minute nap” that starts eight minutes in is really a twelve-minute nap.
Sleep inertia, and how to shorten it.
Sleep inertia is the grogginess in the first minutes after waking, and it is a real, measurable state rather than a feeling. Reaction time, decision-making and mood are all measurably worse for a period after waking, and the effect is strongest when you are woken out of deep sleep.
Three things make it worse: waking out of slow-wave sleep, being sleep-deprived beforehand, and waking during the circadian low point in the early hours. Two things reliably shorten it: light and movement. If you have to be functional straight after a nap, get up, get bright light on your face, and move for a minute or two rather than lying there deciding whether to get up — that decision is being made by the part of you that is least equipped to make it.
The caffeine nap is worth knowing about: caffeine takes roughly twenty to thirty minutes to take effect, so drinking a coffee immediately before a twenty-minute nap means it arrives around the time you wake. It is a real timing trick rather than a folk remedy, though the same caveat applies as to all caffeine — if you are napping at four in the afternoon, that dose is still with you at bedtime.
And a caution that matters more than the rest of this page: if you need to nap most days, the nap is a symptom, not a solution. Persistent daytime sleepiness despite adequate time in bed is worth taking to a doctor rather than managing with audio — sleep apnoea in particular is common, under-diagnosed and treatable, and no amount of good napping compensates for it.
What the sound is actually doing.
Most of the honest value is masking and timing, not entrainment. A steady sound covers the door, the street and the office; a session that ends by itself removes the need to watch the clock. Both help you fall asleep faster. Neither requires you to believe anything about brainwaves.
The theta setting is a defensible default rather than a proven one. Theta activity is characteristic of drowsiness and the transition into sleep, so a 4 Hz beat is at least pointed in the right direction — which is why the power-nap preset uses theta and not delta: delta is the band of the deep sleep you are specifically trying not to reach in twenty minutes. But the evidence that listening to a beat pushes your EEG into the matching band is modest and inconsistent, and the specific claim that it helps you nap has not been tested properly at all. We keep the studies, including the null ones, in the research hub.
Practical settings, in order of how much they matter:
- Volume low. Low enough that you could sleep through it, which is lower than feels right while you are still awake.
- Headphones only for binaural mode. Sleeping in earbuds is uncomfortable and can be a real problem for your ears over time. For a nap on a sofa, use the isochronic version on a speaker, or plain brown noise, which needs no separation at all.
- Let it end. The fade-out is deliberate: a sound that stops gradually is a gentler cue than one that cuts.
- Set a real alarm anyway if something depends on you being awake. This is a timer for the audio, not for you.
If masking the room is the whole job — a partner on a call, traffic, a noisy office — then a noise colour is the better tool and there is no reason to complicate it with a beat. Brown is usually the right choice for low-frequency intrusion; the noise generator has all five.
When in the day to nap.
Early afternoon, and not after about three o’clock if you sleep at a normal time. There is a genuine dip in alertness in the early afternoon that is circadian rather than caused by lunch, and a nap placed in it works with your body clock instead of against it.
The reason for the cut-off is sleep pressure. The longer you are awake, the more of it accumulates, and that pressure is what makes you fall asleep at night. A nap discharges some of it. Nap at five in the afternoon and you have spent, at eleven at night, the exact thing you needed to fall asleep — which is why late napping and insomnia so often travel together.
Shift work inverts all of this, and the ordinary advice does not transfer cleanly: if your night is in the daytime, your nap window moves with it. The general principle survives — nap in the dip, not close to your main sleep — but the clock times do not. The same is true for jet lag, where a badly timed nap is one of the more reliable ways to make the adjustment take longer.
If you are napping because your nights are bad rather than because your afternoon is long, the nap is the wrong lever. Sleep solutions covers the night side, and anxiety at night covers the specific case where it is your head rather than your schedule keeping you up.
Things people reasonably ask.
How long should a power nap be?
Twenty minutes is the usual recommendation, and ten is often better if you can fall asleep quickly. The point is to stay above slow-wave sleep, which you start entering around the twenty-five to thirty minute mark — being woken out of it is what produces the heavy, groggy feeling. Brooks and Lack (2006) compared 5, 10, 20 and 30-minute naps and found the 10-minute nap gave benefits with the least grogginess.
Why do I feel worse after a long nap?
That is sleep inertia. Longer naps take you into slow-wave sleep, and being woken part-way through it leaves measurably impaired alertness and mood for a period afterwards. It passes, but the fix is to avoid it — either nap short enough to stay out of deep sleep, or long enough to complete a full cycle.
What frequency is best for a nap?
Theta, around 4 to 6 Hz, is the defensible default because theta activity is characteristic of drowsiness and the transition into sleep. Deliberately not delta — delta is the band of the deep sleep a twenty-minute nap is trying to stay out of. Be aware that the evidence for audio moving your brain into a band at all is modest.
Do I need headphones for a nap?
Only for binaural mode, where each ear needs its own tone. Sleeping in earbuds is uncomfortable and not great for your ears over time, so for a nap the isochronic mode or plain brown noise on a speaker is usually the better choice.
Will the audio wake me up?
No — it fades out and stops, which is a cue rather than an alarm. If something depends on you being awake at a particular time, set a real alarm as well. The app has progressive wake-up alarms that ramp up gradually instead of jolting you.
What time of day should I nap?
Early afternoon, in the natural dip in alertness, and generally not after about three o’clock if you sleep at a conventional time. Napping late discharges the sleep pressure you need in order to fall asleep that night.
Is the caffeine nap real?
The timing is real: caffeine takes roughly twenty to thirty minutes to take effect, so a coffee immediately before a twenty-minute nap arrives about when you wake. It is a scheduling trick rather than anything special about coffee, and the usual caveat applies — a mid-afternoon dose is still with you at bedtime.
Is napping every day a bad sign?
Not necessarily, but needing to nap most days despite spending enough time in bed is worth raising with a doctor rather than managing with audio. Persistent daytime sleepiness has causes — sleep apnoea is a common and treatable one — and a well-timed nap does not address any of them.