Sleep Cycle Calculator
Sleep runs in roughly 90-minute cycles. Waking at the end of one — rather than in the middle of deep sleep — is the difference between clear-headed and foggy. Enter one time below and we'll do the arithmetic.
Go to bed at one of these times
Times include the 15 minutes it takes an average sleeper to drift off. If you routinely lie awake longer than 30 minutes, that's a sleep-onset problem worth reading about in our insomnia mattress guide.
How to use the results
Pick the earliest bedtime you can realistically keep five nights a week — consistency beats perfect cycle math. If you're waking at the right point in a cycle and still feel wrecked, the problem is usually sleep quality rather than sleep timing: overheating, joint pressure or a partner's movement all fragment cycles without fully waking you.
- Waking hot most nights? Start with our cooling mattress picks.
- Waking with a sore lower back? See best mattresses for back pain.
- Woken by a restless partner? Best mattresses for couples ranks motion isolation.
- Owe yourself hours already? Use the sleep debt calculator.