← All free tools
Free tool
Sleep Cycle Calculator
Waking up mid-cycle is usually why a full night's sleep can still feel groggy. This lines your bedtime or wake time up with full cycles instead.
6 cycles · 9.0h sleepLights out 9:15 PM
5 cycles · 7.5h sleepLights out 10:45 PM
4 cycles · 6.0h sleepLights out 12:15 AM
3 cycles · 4.5h sleepLights out 1:45 AM
Based on average 90 minute sleep cycles plus 15 minutes to fall asleep. Everyone's cycles run a little differently — use this as a starting point, not a rule.
How to use this
- 1Pick whether you're working from a wake-up time or a bedtime.
- 2Enter that time.
- 3Pick whichever option below fits how much time you actually have.
Work Sharp's morning check-in factors in how broken your sleep was, not just how many hours — and adjusts your plan for the day accordingly.
See the full protocol →