About the Sleep Cycle Calculator
What is the Sleep Cycle Calculator?
Sleep runs in cycles of about 90 minutes. Waking at the end of a sleep cycle, rather than in deep sleep, helps you feel less groggy.
Enter when you need to wake up to get the best bedtimes, or when you are going to bed to get the best wake-up times. The recommendation is five cycles (7.5 hours), within the 7–9 hours adults need.
How to use the Sleep Cycle Calculator
- I Want To (sample: Wake up at a set time – when should I sleep?)
- Hour (0–23) (sample: 7)
- Minute (sample: 0)
- Minutes You Take to Fall Asleep (sample: 15)
- Press Find Sleep Times (results also refresh as you type). The result card shows the Recommended Time, along with Based on, Longer option (6 cycles, 9 hours) and Wake-up time.
Formula used
Bedtime = Wake-up time − (Cycles × 90 minutes) − Time to fall asleep
- Cycles = 5 cycles = 7.5 hours; 6 cycles = 9 hours
Cycle length varies from person to person (about 80–110 minutes).
Worked example
These are the sample values already filled in the calculator above, and the result it returns for them:
| Input | Sample value |
|---|---|
| I Want To | Wake up at a set time – when should I sleep? |
| Hour (0–23) | 7 |
| Minute | 0 |
| Minutes You Take to Fall Asleep | 15 |
| Result | Value |
|---|---|
| Recommended Time | 11:15 PM |
| Based on | 5 sleep cycles of 90 minutes (7.5 hours) plus time to fall asleep |
| Longer option (6 cycles, 9 hours) | 9:45 PM |
| Wake-up time | 7:00 AM |
Tips for using the Sleep Cycle Calculator
- Keep the same sleep and wake times every day, including weekends.
- Avoid screens and caffeine in the hour before bed.