Sleep Cycle Calculator

Enter a time you need to wake up — or a time you plan to fall asleep — and the calculator maps out exactly when to set your alarm so you surface between sleep cycles rather than in the middle of one. The logic is straightforward: sleep runs in roughly 90-minute stages, and waking mid-cycle is what leaves you groggy even after a full night in bed. The app accounts for the average 15 minutes it takes to drift off, then lists several ideal wake or bedtime options so you can pick what actually fits your schedule.

It won't track your sleep or connect to a wearable — this is a quick-reference tool you use in the two minutes before you plug your phone in for the night. If you're also working on winding down before bed, Breathing Exercise goes in a different direction but complements the same goal by calming your nervous system before you close your eyes.

Find it alongside other health & fitness tools in the catalog. Works best on mobile, right at bedtime, when you're deciding whether to stay up another hour or just go to sleep now.