Sleep Cycle Calculator (Best Bedtime & Wake Time)
Enter the time you want to wake up, or the time you go to bed, to get bedtime or wake-up times based on 90-minute sleep cycles. Set how long it takes you to fall asleep and see the times that help you wake up refreshed.
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Input
Calculation direction
min
Result
Recommended bedtimes
Times that fall at the edge of a 90-minute sleep cycle, when waking up tends to feel easier.
9:46 PM
6 cycles · about 9 hr
Recommended
11:16 PM
5 cycles · about 7.5 hr
Recommended
12:46 AM
4 cycles · about 6 hr
2:16 AM
3 cycles · about 4.5 hr
How it works
- Sleep moves through light (REM) and deep (non-REM) stages in a cycle of about 90 minutes. This tool treats one cycle as 90 minutes. Waking at the end of a cycle, during lighter sleep, tends to feel more refreshing — these times are a guide based on that idea.
- In 'wake up at' mode, each suggested bedtime is the wake-up time minus (the time it takes to fall asleep + number of cycles × 90 minutes).
- In 'go to bed at' mode, each suggested wake-up time is your bedtime plus (the time it takes to fall asleep + number of cycles × 90 minutes).
- The 'time to fall asleep' (sleep latency) is how long it takes to drift off after getting into bed. The default of 14 minutes is a common average — adjust it to match yourself.
- Options cover 3 to 6 cycles (about 4.5 to 9 hours). Because adults generally need 7–9 hours of sleep, 5–6 cycles (about 7.5–9 hours) are highlighted as recommended.
- Cycle length and ideal sleep duration vary from person to person, so these times will not guarantee a refreshed wake-up. Use them as a general guide, and see a doctor if sleep problems persist.
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