Bedtimes
You are going to bed at 3:00am. When should the alarm be?
Three in the morning is a bedtime almost nobody holds by choice. It belongs to night shifts, to long-haul arrivals and to the occasional night that simply did not end, and the sleep that follows it is the most fragile on this whole list.
In short
If you go to bed at 3:00am, set your alarm for 10:45am. 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. 12:15pm gives you 9h and 9:15am still leaves you 6h.
- Alarm for a full night
- 10:45amAlarm 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 | 12:15pm | 9h | Nine hours. Worth it if you are paying back debt, and more than most adults need every night. |
| 5 | 10:45amAim here | 7h 30m | The target most adults should hold on a normal week. |
| 4 | 9:15am | 6h | Six hours. Short, but a whole number of cycles, so you surface from a lighter patch. |
| 3 | 7:45am | 4h 30m | An emergency night. Fine occasionally, damaging as a pattern. |
Sleeping through a morning is harder than sleeping through a night
By three in the morning your circadian system has already started the climb toward daytime alertness. Core body temperature is on its way up, the melatonin window is closing, and the drive to be awake is rising through exactly the hours you now need to spend asleep. The same eight hours in bed delivers noticeably less sleep than it would starting at eleven.
That is a physiological fact rather than a discipline problem, which is why willpower is the wrong tool for it and the room is the right one. Nobody out-disciplines their own body temperature.
- From 3am, five cycles lands at 11:45am and four at 10:15am
- Sleep taken across a morning is lighter and more broken than the same hours at night
- Total blackout is the single highest-value change available at this hour
One long block beats two short ones
The instinct after a 3am finish is to sleep a few hours, get up for the day and top up later. Split sleep does work for some rotas and it is worse than one consolidated block for most people, because each stretch has to get through the shallow early cycles again and you spend proportionally more of the total in light sleep.
If the day genuinely has to be broken into two, the useful version is one long anchor block and one short nap rather than two medium ones, and the nap should end well before the next sleep period.
Nap lengths and what each one actually buys are at /naps, and the rota version of this problem at /for/shift-rotating-nurses.
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 10:45am 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,10:45am 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
If I go to bed at 3am what time should I wake up?
Five sleep cycles puts the alarm at 11:45am, which is seven and a half hours of sleep. Four cycles is 10:15am at six hours and three is 8:45am at four and a half. Each includes about fifteen minutes to fall asleep.
Why is it harder to sleep after 3am?
Because your circadian system has already begun the shift toward daytime alertness. Core temperature is rising and the melatonin window is closing, so the drive to stay awake is working against you for the whole of the sleep you are trying to take. The room being dark and quiet matters much more than usual.
Should I stay up instead of sleeping for a few hours?
Almost never. Even a short block of sleep discharges some sleep pressure and performs better than none, and staying awake through a full night pushes you into a period of impairment that a single normal night does not fully clear. If the choice is three hours or nothing, take the three hours.
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 10:00pmWhere to put the alarm after a 10:00pm 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.
Elsewhere on the site
A different corner of the same problem.
- RoundupsThe best sleep trackers that don't need a watchTock is the best sleep tracker without a watch. Leave the phone on the nightstand and it uses the microphone and accelerometer all night, classifies snores, coughs and sleep talking on device, and hands you a report plus the audio in the morning. SleepScore is the strongest alternative if you would rather nothing listened to the room.
- Wake timesWaking up at 7:30amBedtimes by sleep cycle for a 7:30am alarm.
- Sleep by ageHow much sleep teenagers needThe American Academy of Sleep Medicine recommends that teenagers aged 13 to 18 years sleep 8 to 10 hours per 24 hours on a regular basis. The obstacle is a genuine biological shift: the adolescent circadian rhythm runs later, so a teenager cannot reliably fall asleep at the time an early school start requires.
- NapsThe coffee napA coffee nap means drinking caffeine and then immediately napping for about 20 minutes. Caffeine takes roughly 20 to 30 minutes to have a noticeable effect, so it does not stop you falling asleep quickly, and you wake as it takes hold. The two effects add rather than cancel.
- Wake tonesKalimbaKalimba is Tock's thumb-piano wake tone: warm plucked notes with a short woody decay that lift you rather than startle you. It still runs on Apple's AlarmKit, so a silent switch, an active Focus and a closed app make no difference to whether it goes off.
- Head to headCalm vs Headspace SleepIf you want to be told a story by a voice you recognise, Calm has the deeper and better-produced library. If you want to be taught a wind-down and nudged to keep at it, Headspace's course structure does more for you.
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 10:45am for a lighter moment and rings then, and your set time is always the fallback.