What time to go to bed
We sleep in cycles of about ninety minutes. If the alarm catches you halfway through one, you get up wrecked even after eight hours.
Go to bed at one of these times
09:45 PM6 cycles · 9 h
11:15 PM5 cycles · 7 h 30 minIdeal
12:45 AM4 cycles · 6 h
02:15 AM3 cycles · 4 h 30 min
FreeNo sign-up90-minute cyclesCounts the 15 to fall asleepAny device
The maths uses 90-minute cycles and adds 15 minutes to fall asleep, which is the usual reference. Everyone is different and this is not medical advice: if you sleep badly on a regular basis, that is for a professional, not a calculator.
Frequently asked questions
Why 90-minute cycles?
Sleep moves in cycles of about an hour and a half. Waking at the end of one feels easy; waking in the middle is what leaves you groggy.
How do I use it?
Tell it what time your alarm rings and it gives you the bedtimes that fit whole cycles — pick the one your evening allows.
Does it count the time it takes to fall asleep?
Yes, it adds the average 15 minutes people need to drift off, so the times you see are when to get INTO bed.
Is eight hours not the rule then?
Eight hours is a good average, but waking between cycles matters as much as the total — five full cycles beat five and a half broken ones.
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