Bedtimes
You are going to bed at 8:30pm. When should the alarm be?
Half past eight is the hour that makes a five in the morning start survivable. It is early enough to be socially expensive and late enough that most people can actually fall asleep, which is a narrower window than it sounds.
In short
If you go to bed at 8:30pm, set your alarm for 4:15am. 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. 5:45am gives you 9h and 2:45am still leaves you 6h.
- Alarm for a full night
- 4:15amAlarm 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 | 5:45am | 9h | Nine hours. Worth it if you are paying back debt, and more than most adults need every night. |
| 5 | 4:15amAim here | 7h 30m | The target most adults should hold on a normal week. |
| 4 | 2:45am | 6h | Six hours. Short, but a whole number of cycles, so you surface from a lighter patch. |
| 3 | 1:15am | 4h 30m | An emergency night. Fine occasionally, damaging as a pattern. |
The bedtime that makes a 5am alarm honest
A lot of people set a 5am alarm and go to bed at eleven. That is six hours before the latency, and it is not a schedule, it is a slow deficit. An 8:30pm lights-out is what a 5am start looks like when the arithmetic is done rather than hoped at.
The people who hold this reliably are almost always doing it for a fixed early commitment: a commute that has to beat traffic, a gym that opens at six, a farm, a bakery, small children who are up at half five whatever anybody thinks. What they have in common is that the wake time is not negotiable, so the bedtime is where the adjustment has to happen.
- From 8:30pm, five cycles lands at 5:15am and six lands at 3:45am
- This is roughly the earliest bedtime most non-morning types can reach without lying awake
- It costs the second half of the evening, which is the real reason people abandon it rather than any difficulty sleeping
Hold it at the weekend or do not bother
An 8:30pm bedtime on weeknights and a midnight bedtime on Friday and Saturday is a three and a half hour swing, which is a time zone. Your body clock treats it as one, and Monday morning is the jet lag. The name for this is social jetlag and it is measurable in exactly the way it feels.
The version that works is a smaller swing: an hour later at the weekend rather than three, with the wake time moving less than the bedtime. Anchoring the morning is more effective than anchoring the evening, because light after waking is what actually sets the clock.
More on the mechanism at /glossary/social-jetlag, and the practical version 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 4:15am 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,4:15am 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 8:30pm what time should I wake up?
Five sleep cycles puts the alarm at 5:15am, which is seven and a half hours asleep and the target most adults should hold. Four cycles is 3:45am at six hours, and six cycles is 6:45am at nine hours. Each figure adds fifteen minutes for the time it takes to fall asleep.
Is going to bed at 8:30pm healthy?
There is nothing unhealthy about the hour itself. What matters is total sleep and consistency, not where the block sits on the clock, provided it is dark when you sleep. An early bedtime held seven days a week is better for you than a late one you keep moving around.
How do I fall asleep at 8:30pm when it is still light?
Blackout blinds or a proper mask, and dim the indoor lighting for the ninety minutes before bed rather than only at the moment you get in. Evening light delays melatonin, so the room being dark at 8:30 matters much less than the room being dim from seven.
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 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.
- 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 tonesAnnoying alarm soundsAn unbearable alarm tone works for roughly a week. After that you learn to silence it before you are properly conscious, and you are back where you started with a worse mood attached. The durable fix is not a harsher sound, it is making the alarm end somewhere your half-asleep self cannot reach.
- Head to headAutoSleep vs PillowAutoSleep suits the person who wants every number and no recurring bill. Pillow suits the person who wants the night caught automatically and presented calmly, then written properly into Apple Health.
- 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 youSnorersSomeone has told you that you snore, or you have woken yourself up doing it, and you have no idea how loud it really is or whether it is the kind of thing that matters.
- AlternativesTock vs Sleep CycleSwitch to Tock if you want the alarm itself to be different: a system alarm that rings on silent and through a Focus, moved up to 30 minutes earlier into a lighter moment, with a task before it stops. Stay with Sleep Cycle if you have years of history in it, or if someone in the house is on Android.
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 4:15am for a lighter moment and rings then, and your set time is always the fallback.