Bedtime calculator
Sleep runs in cycles of roughly 90 minutes. Waking at the end of one feels far easier than being dragged out of the middle. Tell us when you need to wake up, and we'll work backwards.
Why 90 minutes?
A full night of sleep is a series of cycles, each moving through light sleep, deep sleep, and REM. One cycle takes about 90 minutes on average, though the real range runs from about 70 to 120 minutes and shifts across the night. That's why these times are good targets rather than guarantees.
The calculator also adds 15 minutes for falling asleep, which is about typical for a healthy sleeper. If you know you take longer, shift your bedtime earlier by the difference.
The honest caveat
The biggest wins come from consistency, a dark cool room, and managing caffeine, and no calculator replaces those. Cycle timing is the fine-tuning, worth doing once the basics are in place. If you want to know which basics need work, take the sleep score quiz.