Sleep Calculator guide
Sleep Calculator: When to Go to Bed and Wake Up
Use our sleep calculator to find the best time to go to bed or wake up, based on 90-minute sleep cycles and the time it takes to fall asleep.
By the AllCalculator editorial teamUpdated 16 October 20261 min read
Ever woken up feeling groggy even after a full night's sleep? It might be because your alarm went off in the middle of deep sleep. Our Sleep Calculator suggests times that fit your natural sleep cycles.
How to use the calculator (Sleep Calculator)
- Choose whether you know when you want to wake up or when you're going to bed.
- Enter the time.
- Enter how long it usually takes you to fall asleep.
You'll see the best times for 3 to 6 full sleep cycles.
Sleep cycles
Sleep happens in cycles of about 90 minutes, moving from light sleep to deep sleep to dream (REM) sleep. Waking at the end of a cycle, when sleep is lightest, can help you feel more refreshed.
A worked example
With the calculator's default settings, to wake at 7:00 after 5 sleep cycles (7½ hours), allowing 15 minutes to fall asleep, go to bed at 23:15.
How much sleep do you need?
| Age | Hours a night |
|---|---|
| School age (6–12) | 9–12 |
| Teenagers (13–18) | 8–10 |
| Adults | 7–9 |
| Older adults (65+) | 7–8 |
Tips for better sleep
- Go to bed and get up at the same time every day.
- Keep your bedroom dark, quiet and cool.
- Avoid caffeine in the afternoon and big meals late at night.
- Put screens away an hour before bed.
Frequently asked questions
Are sleep cycles always 90 minutes?
No, they range from about 70 to 120 minutes and vary through the night, so use the times as a guide.
When should I see a doctor?
If you regularly struggle to sleep, feel tired all the time, or someone tells you that you stop breathing or snore loudly, speak to your GP.
Sources and further reading
Links open official and independent websites in a new tab.
This guide is general information to help you understand your options. It isn't financial, tax, legal or building advice and doesn't take your personal circumstances into account. Figures were checked when the guide was last updated and can change, so confirm anything important with GOV.UK, HMRC, a regulated adviser or a qualified tradesperson.