VITALWork out your bedtime
Be in bed with the lights out by
10:45 pm
Start winding down at
9:45 pm
Be in bed with the lights out by 10:45 pm, and start winding down at 9:45 pm. That allows 8 hours of sleep after about 15 minutes to fall asleep, before waking at 7:00 am.
Another way: 90-minute cycles
A rough rule of thumb. Sleep runs in cycles that average about 90 minutes, so some people aim for a whole number of them. These bedtimes also allow for the time you take to fall asleep.
- 11:15 pm for 5 cycles, about 7 hours 30 minutes of sleep. Closest to the sleep you chose
- 9:45 pm for 6 cycles, about 9 hours of sleep
Everything is worked out in your browser. Nothing you enter leaves this page or is saved.
How the calculator works
It counts back from the time you need to wake up. It subtracts the sleep you want, then the time you usually take to fall asleep, and what is left is when to be in bed with the lights out. The wind-down time is an hour earlier, as a gentle prompt to put your phone away and relax. The NHS advises setting aside time to relax before bed, so change that hour to suit you.
How much sleep to choose
The age group gives a starting point from the National Sleep Foundation’s recommendations for healthy people: 8 to 10 hours for teenagers, 7 to 9 hours for adults and 7 to 8 hours for people aged 65 and over. The slider lets you set your own. If you are not sure what suits you, how much sleep you need explains how to find your number over a couple of regular weeks.
Time to fall asleep
The Sleep Foundation says adults typically take about 10 to 20 minutes to fall asleep, so 15 is a reasonable first guess. Change it if your own nights are quicker or slower. If you regularly take much longer than 20 to 30 minutes, it may be worth speaking to a GP.
The 90-minute cycle option
Sleep moves through lighter and deeper stages in cycles. The Sleep Foundation says they average about 90 minutes, ranging from around 70 to 120, with the first often the shortest. Cleveland Clinic gives 90 to 120 minutes. Some people like to pick a bedtime that makes a whole number of cycles, and the alternatives in the calculator do that sum.
Treat it as a rough rule of thumb. Cycle lengths differ between people and across the night, so the times will not line up exactly, and getting enough sleep overall matters more than landing on a cycle. We show the six-hour option only when you choose less than 7 hours, because most adults are advised to get more than that.
Your times stay on your device
The calculator runs in your browser and uses no outside libraries. The times and numbers you enter are not sent anywhere or saved.
In Vital
Vital reads your sleep from Apple Health, with or without an Apple Watch, and learns how much sleep you seem to need from your own nights. It then suggests a bedtime for you.
Get Vital for iPhoneCommon questions
What time should I go to bed?
Count back from the time you need to wake up. Subtract the sleep you want, then the time it usually takes you to fall asleep. For a 7:00 am alarm, 8 hours of sleep and 15 minutes to fall asleep, that is 10:45 pm.
Does waking at the end of a 90-minute cycle really help?
Sleep cycles average about 90 minutes, but they vary between people and across the night, so the arithmetic is only a rough guide. Treat the cycle times as options to try, and put getting enough sleep overall first.
How long should it take to fall asleep?
The Sleep Foundation says adults typically take about 10 to 20 minutes. Falling asleep almost immediately can be a sign of not getting enough sleep, and regularly taking much longer than 20 to 30 minutes may point to insomnia or another sleep issue worth raising with a GP.
Does the calculator save or send my times?
No. The sum is done in your browser. The times and numbers you enter are not sent anywhere and are not saved.
Vital gives general information about fitness and wellbeing. It is not medical advice, and it does not diagnose or treat any condition. If you often struggle to sleep, speak to a GP or pharmacist.