Bedtime calculator
Start from your alarm. We'll count back in whole sleep cycles and tell you when the lights need to go off.
Adjust for how you sleep
Most adults fall asleep in 10 to 20 minutes. If you wake up groggy even at the suggested times, try an 85 or 95 minute cycle for a week.
Picking a bedtime you'll actually keep
Most of us decide our bedtime by accident. Dinner runs late, a reel turns into twenty, and suddenly it's 12:40. Working backwards from the alarm flips that around: the morning is fixed, so the night gets planned to fit it.
The calculator gives you four bedtimes. Here's how to choose between them:
- Five cycles (7.5 hours) is the default for adults. It's realistic on a workday and leaves you waking from light sleep.
- Six cycles (9 hours) is right for teenagers, for weeks when you're unwell, and when you're paying back lost sleep.
- Four cycles (6 hours) is a short night. Fine before an early flight, not fine five days a week.
- Three cycles (4.5 hours) is damage control. If this is your only option, plan a 20 minute nap the next afternoon.
Make the bedtime stick
A bedtime is really the end of a 30 to 60 minute wind-down. Set a reminder for half an hour before it (the calculator can add one to your phone's calendar), then:
- Put the phone on charge outside arm's reach. If it's your alarm, use the cheapest alarm clock you can find instead.
- Switch from bright white tube lights to a warm, dim lamp.
- Do something slow and offline: a book, light stretching, a shower, folding clothes.
- Lie down at the time the calculator gave you, not when you finally feel sleepy.
Stick to the same wake-up time on Sunday too. Shifting it by two hours at the weekend gives you something like jet lag every Monday.
Questions people ask
What time should I go to bed to wake up at 5 AM?
For a 5:00 AM alarm, go to bed at 9:15 PM to get five full cycles (7.5 hours), or 7:45 PM for six. If that's too early for your household, 10:45 PM gives four cycles (6 hours), which is a short but clean night.
Should I go to bed when I feel sleepy or at a fixed time?
Both, ideally. Use the calculated bedtime as your target and start winding down 30 minutes before it. If you lie in bed for more than 20 minutes wide awake, get up, sit somewhere dim, and come back when you feel drowsy. Keep the wake-up time fixed no matter what.
Is going to bed at midnight bad if I still sleep 7.5 hours?
Not by itself. Total sleep and consistency matter more than the clock. The trouble in practice is that a midnight bedtime with a 6 or 6:30 AM alarm leaves you short. If your mornings are early, your nights need to be too.
Why does the calculator add 15 minutes?
That's the average time a healthy adult takes to fall asleep. If you drop off in five minutes or toss for half an hour, change the setting under 'Adjust for how you sleep' and the bedtimes will shift.