Bedtimes
You are going to bed at 1:30am. When should the alarm be?
Half past one is usually not a plan. It is what is left after a shift finished late, a deadline ran over or a night simply got away, and the useful advice for it is about damage control rather than about ideal schedules.
In short
If you go to bed at 1:30am, set your alarm for 9:15am. 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. 10:45am gives you 9h and 7:45am still leaves you 6h.
- Alarm for a full night
- 9:15amAlarm 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 | 10:45am | 9h | Nine hours. Worth it if you are paying back debt, and more than most adults need every night. |
| 5 | 9:15amAim here | 7h 30m | The target most adults should hold on a normal week. |
| 4 | 7:45am | 6h | Six hours. Short, but a whole number of cycles, so you surface from a lighter patch. |
| 3 | 6:15am | 4h 30m | An emergency night. Fine occasionally, damaging as a pattern. |
The bedtime that is usually a leftover
Very few people choose 1:30am as a routine. It shows up after late shifts, after travel, after the kind of evening that does not end so much as stop. Which means the honest version of this page is not about optimising a schedule, because there is not one, it is about what to do with the hours that are left.
The first thing worth knowing is that a whole number of cycles beats a round number of hours when the night is short. Four cycles finishing at 8:45am will generally leave you in better shape than six and a half hours ending at 8:15am, even though the second one is more sleep, because of where the alarm lands.
- From 1:30am, four cycles lands at 8:45am and three at 7:15am
- On a short night, where the alarm falls matters more than it does on a long one
- A single late night is recoverable; the pattern is what does the damage
Protect the morning after, not the night itself
The night is already short by the time you are reading this, so the leverage has moved to the morning. Getting bright light soon after waking, keeping the wake time close to your normal one, and not napping late are the three things that stop one late night turning into three.
The temptation is to sleep in as far as possible, and a moderate lie-in is fine. A four hour one shifts your clock, which means the following night starts late as well, which is how a single late finish becomes a week.
If late finishes are a rota rather than an accident, /for/night-shift-workers is the more useful page.
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 9:15am 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,9:15am 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 1:30am what time should I wake up?
Four sleep cycles puts the alarm at 8:45am, which is six hours of sleep, and five cycles takes you to 10:15am at seven and a half. Three cycles is 7:15am at four and a half hours, which is an emergency night rather than a plan.
Is it better to get four hours or six hours of sleep?
Six, and it is not close. Both are short, but four and a half hours is roughly three cycles and six is four, and the cost of short sleep is not linear. If the choice is between waking at the end of a cycle or getting an extra twenty minutes inside one, take the cycle boundary.
How do I recover from a night of very little sleep?
Keep the wake time close to normal, get bright light soon after it, avoid a long or late nap, and go to bed at your usual time rather than very early. A moderate lie-in is fine. A four hour one moves your body clock and turns one bad night into several.
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 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.
- RoundupsThe best sleep apps for studentsFor most students the best answer is free: the iPhone Clock app, a wake time you keep at weekends, and Alarmy's free tier if you sleep through things. Tock is the paid pick worth the money once you have tried that and still miss 9am lectures.
- Wake timesWaking up at 8:30amBedtimes by sleep cycle for a 8:30am alarm.
- Sleep by ageHow much sleep preschoolers needThe American Academy of Sleep Medicine recommends that children aged 3 to 5 years sleep 10 to 13 hours per 24 hours, including naps, on a regular basis. This is the final band where daytime sleep counts toward the total; from age 6 the figures are given per night.
- NapsThe 60 minute napA 60 minute nap includes a substantial amount of slow wave sleep, which is useful for recovery and for some kinds of memory, and it usually ends before the cycle completes. That means the benefit is real and the wake-up is often groggy, so it suits situations where the hour afterwards is flexible.
- Wake tonesMusic boxMusic box is Tock's slowest and most nostalgic wake tone, a thin bell-like melody that unwinds instead of alerting. It rings reliably through silent mode because Tock's alarms run on Apple's AlarmKit, but as a tone it is the weakest choice in the set for anyone who genuinely sleeps hard.
- Head to headApple Health Sleep vs RiseApple is the better record and Rise is the better plan. If you keep opening your stage chart and still don't know what to change, Rise is the one built to answer that.
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 9:15am for a lighter moment and rings then, and your set time is always the fallback.