Bedtimes
You are going to bed at 11:30pm. When should the alarm be?
Half past eleven is the point where a standard working morning stops adding up. It is a perfectly good bedtime for a nine o clock start and a slow deficit for anything earlier, and most people running it are doing the second while telling themselves it is the first.
In short
If you go to bed at 11:30pm, set your alarm for 7:15am. 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. 8:45am gives you 9h and 5:45am still leaves you 6h.
- Alarm for a full night
- 7:15amAlarm 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 | 8:45am | 9h | Nine hours. Worth it if you are paying back debt, and more than most adults need every night. |
| 5 | 7:15amAim here | 7h 30m | The target most adults should hold on a normal week. |
| 4 | 5:45am | 6h | Six hours. Short, but a whole number of cycles, so you surface from a lighter patch. |
| 3 | 4:15am | 4h 30m | An emergency night. Fine occasionally, damaging as a pattern. |
Fine for a late start, expensive for a normal one
From 11:30pm, five cycles finish at 8:15am. If your day genuinely starts at nine, that is a complete night and there is nothing to fix. If your alarm is at seven, you are getting about seven hours of opportunity and closer to six and a half of sleep, every weeknight, which is roughly three hours short across a working week.
The reason this hour is so common has less to do with chronotype than with what the evening is for. Late bedtimes cluster around the only stretch of the day that belongs to nobody else, and the thing being protected is not entertainment so much as the first unclaimed hour since morning.
- From 11:30pm, five cycles lands at 8:15am and four at 6:45am
- With a 7am alarm this is a six and a half hour night five days a week
- Naming what the late hour is protecting makes it easier to move than deciding to have more discipline
Move the wake time first, not the bedtime
The instinct when trying to shift a late schedule is to get into bed earlier, which mostly produces an hour of lying awake, because the body clock has not moved and melatonin has not arrived. The lever that actually works points the other way: hold the wake time, get bright light into your eyes soon after it, and let the evening sleepiness arrive earlier on its own.
That takes several days rather than one night, and it is the whole difference between a schedule that shifts and one that snaps back on the first weekend.
The full method is at /guides/how-to-fix-your-sleep-schedule.
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 7:15am 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,7:15am 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 11:30pm what time should I wake up?
Five sleep cycles puts the alarm at 8:15am, which is seven and a half hours asleep. Four cycles is 6:45am at six hours. Both figures include the fifteen minutes it usually takes to fall asleep.
How much sleep do I get from 11:30pm to 7am?
Seven and a half hours in bed and about seven and a quarter asleep. That is just over the seven hour adult figure but it lands between four and five full cycles, so a 7am alarm will often interrupt one rather than follow it.
How do I move my bedtime earlier from 11:30pm?
Shift the morning before the evening. Hold a fixed wake time, get bright light soon after waking, and dim the house for the ninety minutes before bed. Sleepiness moves earlier by itself over about a week. Getting into bed an hour earlier on night one mostly buys an hour of lying awake.
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 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 tonesSunrise alarmA sunrise alarm clock is a bedside lamp that brightens over roughly 20 to 30 minutes before your set time, and the light is the part you are paying for. Tock is an iPhone app with no light hardware at all, so it takes the timing half instead: a soft wake tone rung at a lighter moment inside the last 30 minutes rather than at a fixed time.
- Head to headCalm vs Sleep CycleIf the problem is lying awake with a busy head, Calm. If the problem is groggy mornings and having no idea what your nights look like, Sleep Cycle. Most people searching this have already decided which; they just have not said it out loud.
- FeaturesSnore recordingTock keeps short audio clips of the things it hears in the night and pins each one to the minute it happened. Snoring, coughing and sleep talking are labelled by name, and every clip has a play button in the morning.
- Sleep soundsLate cafeA cafe bed works because a room with people in it reads as safe, and it only keeps working while none of the voices are intelligible. The moment you can pick out a word you start following it, and following language is the opposite of falling asleep, which is why Tock generates the murmur instead of recording a real room.
- Tock for youTravellers with jet lagYou landed, you are on local time on paper, and your body is running four or eight hours behind. Wide awake at 3am, unusable at 3pm, and it lasts roughly a day per time zone.
- AlternativesTock vs RiseChoose Rise if planning your day around energy peaks and a running sleep debt is what actually changes your behaviour. Choose Tock if you want the alarm itself to be smarter, the night recorded from the phone, and a coach that can talk about what it heard.
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 7:15am for a lighter moment and rings then, and your set time is always the fallback.