Health & Fitness
Sleep Calculator
Find the best bedtimes for your wake-up time, based on 90-minute sleep cycles.
Sleep Calculator
Assumes 15 minutes to fall asleep and 90-minute sleep cycles.
How to use the sleep calculator
Sleep runs in roughly 90-minute cycles. Waking at the end of a cycle feels far better than waking mid-cycle. Enter your wake-up time to see the bedtimes that give you 6, 5 or 4 complete cycles.
Most adults need 7–9 hours of sleep. The 5-cycle (7.5h) option is a good default for many people.
Frequently asked questions
What time should I go to bed?
Aim to finish a full 90-minute cycle shortly before you wake. Enter your wake time here and pick a bedtime that gives 5 cycles (7.5 hours) for most adults.
Why 90-minute cycles?
Human sleep cycles through light and deep sleep last about 90 minutes on average. Waking between cycles leaves you more refreshed.
How much sleep do adults need?
Most adults need 7–9 hours per night. Fewer than 6 hours regularly can affect health and focus.
Does this account for falling asleep?
Yes — it adds about 15 minutes to fall asleep before the first cycle begins.