Wake up at the end of a sleep cycle, not in the middle of one. Enter a time below and get your best options.
Sleep happens in cycles of roughly 90 minutes, moving through light sleep, deep sleep, and REM. Waking up in the middle of a cycle — especially deep sleep — is what makes mornings feel groggy, even after plenty of hours in bed.
This calculator counts backward or forward in 90-minute blocks, plus about 15 minutes to fall asleep, so you land on a wake-up point between cycles instead of inside one. Most adults do well with 5 to 6 full cycles a night (7.5–9 hours).
A single well-timed night helps, but a steady sleep and wake schedule matters more over time. Try to keep your wake-up time within the same 30-minute window daily, even on weekends.