Sleep Calculator: When to Go to Bed

How the time is calculated

Bed­time = wake-up time − the sleep you need − the time it usu­al­ly takes you to fall asleep. The cal­cu­la­tor shows op­tions for 9, 8 and 7 hours of sleep.

The Amer­i­can Acad­e­my of Sleep Medicine rec­om­mends that adults reg­u­lar­ly sleep at least 7 hours a night (AASM, 2015). How much you per­son­al­ly need varies — let how you feel during the day guide you.

Why there are no “90-minute cycles” here

Sleep moves through sev­er­al cycles of dif­fer­ent stages each night, but their length varies from person to person and changes through the night (NHLBI). A clock or a cal­cu­la­tor can’t mea­sure your sleep stages, so a fixed 90-minute rule can’t pick the “right” moment to wake. Plan­ning enough sleep is more re­li­able.

When to talk to a doctor

If you reg­u­lar­ly sleep 7–9 hours and still wake tired, snore loudly with pauses in breath­ing, nod off during the day at the wrong mo­ments, or strug­gle to fall asleep most nights, talk to your doctor.

Falling asleep more easily

A steady wake-up time, even on week­ends, dim light and fewer screens in the hour before bed, a cool dark bed­room and a calm evening rou­tine all help.