Bedtimes
You are going to bed at 10:00pm. When should the alarm be?
Ten o clock is the most common adult bedtime there is, and for once the popular answer is close to the right one. It fits a normal working morning with a full night underneath it and does not require rearranging your evening around your sleep.
In short
If you go to bed at 10:00pm, set your alarm for 5:45am. That is 7h 30m of sleep across 5 full cycles, plus the fifteen minutes it takes most people to actually fall asleep, so you wake at the end of a cycle rather than inside one. 7:15am gives you 9h and 4:15am still leaves you 6h.
- Alarm for a full night
- 5:45amAlarm for a full night5 cycles, 7h 30m asleep
- Length of an average sleep cycle
- 90 minLength of an average sleep cycleReal ones run 70 to 120
- Added before the first cycle
- 0h 15mAdded before the first cycleMost calculators forget this
| Cycles | Set the alarm | Time asleep | What it is good for |
|---|---|---|---|
| 6 | 7:15am | 9h | Nine hours. Worth it if you are paying back debt, and more than most adults need every night. |
| 5 | 5:45amAim here | 7h 30m | The target most adults should hold on a normal week. |
| 4 | 4:15am | 6h | Six hours. Short, but a whole number of cycles, so you surface from a lighter patch. |
| 3 | 2:45am | 4h 30m | An emergency night. Fine occasionally, damaging as a pattern. |
The default, and why the default is defensible here
Most sleep advice that names an hour names this one, and unusually it is not lazy. Ten sits near the middle of where adults naturally get sleepy, it leaves an evening long enough to have a life in, and it puts a seven o clock alarm at roughly eight and a half hours of opportunity. Very few schedules do all three.
It is also the bedtime that makes the standard advice arithmetic work without heroics. Seven or more hours is the consensus figure from the American Academy of Sleep Medicine, and a 10pm lights-out clears it comfortably for any alarm from 5:15am onwards.
- From 10pm, five cycles lands at 6:45am and six at 5:15am
- A 7am alarm gives about eight hours and forty five minutes of opportunity
- It is the least disruptive bedtime to actually hold, which is why it survives where earlier ones do not
If 10pm is already your bedtime, the problem is elsewhere
A reader who is already going to bed at ten and still waking up badly does not have a bedtime problem. There are only three other places for it to be: how long it actually takes you to fall asleep, how many times the night gets broken, and which part of a cycle the alarm lands in.
The first two are things you have to measure rather than guess, because nobody remembers their own wake-ups accurately. The third is the one that is fixable tonight, and it is what a smart alarm does: watch the half hour before the alarm and ring at a lighter moment inside it.
Tracking without a wearable is covered at /guides/sleep-tracking-without-a-wearable, and what a phone can honestly hear at /blog/what-your-phone-can-actually-hear-at-night.
The table is an average, and your night is not
Ninety minutes is the number everybody quotes because it is roughly the mean. A real night does not run to it. Your first cycle tends to be short, the middle ones stretch, and by the last couple of hours you are cycling faster with more of each one spent in light sleep and REM. So the arithmetic above gets you to approximately the right alarm, and then the last half hour is a coin toss.
That coin toss is the entire argument for a smart alarm, and it is why this page ends with one rather than with a schedule. Tock spends the thirty minutes before 5:45am watching for the moment you are already stirring, on two channels: movement from the accelerometer and sound from the microphone. When it finds one it rings a little early. When it does not,5:45am rings exactly as you set it, so the fallback is never worse than a normal alarm. You can read the mechanism at how smart wake works, or start with sleep cycles explained if the arithmetic itself is the part you want to understand properly.
Questions people ask
What time should I wake up if I go to bed at 10pm?
Five full sleep cycles puts the alarm at 6:45am, which is seven and a half hours asleep and the right target for most adults. Six cycles is 5:15am at nine hours, and four is 8:15am at six. All of these add fifteen minutes for the time it takes to fall asleep.
Is 10pm to 6am enough sleep?
It is about seven and three quarter hours of sleep once you allow for dropping off, which clears the seven hour consensus figure for adults comfortably. It sits between five and six cycles, so the alarm may land mid-cycle and leave you groggier than the total would suggest.
Why am I tired after going to bed at 10pm?
Usually one of three things: it takes you longer to fall asleep than you think, the night is being broken by noise or by waking without remembering it, or the alarm is pulling you out of deep sleep. The total in bed can be right while all three of those go wrong, which is why measuring a night beats estimating one.
Other bedtimes
The same arithmetic, run from a different lights-out.
- Going to bed at 8:00pmWhere to put the alarm after a 8:00pm lights-out.
- Going to bed at 8:30pmWhere to put the alarm after a 8:30pm lights-out.
- Going to bed at 9:00pmWhere to put the alarm after a 9:00pm lights-out.
- Going to bed at 9:30pmWhere to put the alarm after a 9:30pm lights-out.
- Going to bed at 10:30pmWhere to put the alarm after a 10:30pm lights-out.
- Going to bed at 11:00pmWhere to put the alarm after a 11:00pm lights-out.
- Going to bed at 11:30pmWhere to put the alarm after a 11:30pm lights-out.
- Going to bed at 12:00amWhere to put the alarm after a 12:00am lights-out.
- Going to bed at 12:30amWhere to put the alarm after a 12:30am lights-out.
- Going to bed at 1:00amWhere to put the alarm after a 1:00am lights-out.
- Going to bed at 1:30amWhere to put the alarm after a 1:30am lights-out.
- Going to bed at 2:00amWhere to put the alarm after a 2:00am lights-out.
- Going to bed at 3:00amWhere to put the alarm after a 3:00am lights-out.
Elsewhere on the site
A different corner of the same problem.
- Wake timesWaking up at 5:00amBedtimes by sleep cycle for a 5:00am alarm.
- Sleep by ageHow much sleep older adults needThe American Academy of Sleep Medicine recommendation of 7 or more hours per night applies to adults without an upper age cut-off. What changes with age is not how much sleep is needed but how easily it is obtained: the night becomes lighter, more broken, and shifts earlier.
- NapsThe 30 minute napA 30 minute nap frequently ends inside slow wave sleep, which produces the strongest sleep inertia of any nap length. That is the heavy, disoriented feeling that can take twenty minutes or more to clear, and it is why 20 minutes or a full 90 minute cycle are both better choices.
- Wake tonesGentle alarm soundsA gentle alarm works when it catches you at a light moment and fails when it lands in the heaviest part of your night, which is a timing problem rather than a volume one. Tock watches movement and sound across the 30 minutes before your alarm and rings early at a lighter moment if it finds one, with your set time as the fallback.
- Head to headApple Health Sleep vs PillowApple's built-in tracking is enough if you want hours and stages and nothing more. Pillow is for the Watch wearer who finds Apple's presentation too thin and wants the night detected and shaped for them without pressing anything.
- FeaturesSleep scoreThe sleep score is a single number for a night, sitting at the top of that night detail view. Underneath it are the parts that produced it, and across nights the insights cover 21 metrics in 7 groups plus long-run measures like sleep regularity and sleep debt.
Tomorrow, you wake up just before your alarm
Setting the alarm on a cycle boundary is arithmetic and your night is not. Tock watches the half hour before 5:45am for a lighter moment and rings then, and your set time is always the fallback.