Sleep Cycle Calculator: What Time Should You Go to Bed?

Tell it when you need to wake and this gives you the bedtimes that line up with full 90-minute sleep cycles, so the alarm catches you in light sleep rather than deep sleep. Tired brains wander far more, which is why protecting sleep beats almost every focus technique.

A full sleep cycle runs about 90 minutes, moving from light sleep down into deep sleep and back up through dreaming. Waking at the top of a cycle, in light sleep, feels far easier than an alarm dragging you out of deep sleep. The cycle length is an average, so let these times guide your routine rather than treating them as exact to the minute. Most adults do best on five or six full cycles, which is roughly seven and a half to nine hours.