Wake up refreshed by timing your sleep around full sleep cycles.
What is the Sleep Calculator?
Waking up in the middle of a sleep cycle makes you feel groggy. This sleep calculator uses 90-minute sleep cycles to suggest the best bedtime for your alarm, or the best wake-up time if you go to bed now.
How to use the Sleep Calculator
- Choose whether you know your wake-up time or your bedtime.
- Enter the time and how long you usually take to fall asleep.
- Pick one of the suggested times – 5 or 6 cycles is ideal for most adults.
Frequently asked questions
How many hours of sleep do I need?
Most adults need 7–9 hours a night, which is about 5–6 full sleep cycles.
Why 90 minutes?
An average sleep cycle, from light sleep to deep sleep to REM, lasts about 90 minutes.
This sleep calculator is 100% free, needs no signup and runs in your browser, so your data stays private.
Last updated: · By NodifyTech