How to use it
- Choose whether you know your wake-up time or your bedtime.
- Enter the time and pick how long you'd like to sleep.
- Adjust how long it usually takes you to fall asleep.
- Review the suggested time and alternatives, then copy or save them.
Understanding your results
Your main result uses the sleep duration you chose. Alternatives show shorter and longer options spaced roughly one typical sleep cycle apart (about 90 minutes) — a helpful planning guide, not an exact prediction. Cycle length differs between people and across the night.
How much sleep do people need?
General guidance from sleep organizations suggests roughly: teens (13–18) 8–10 hours; adults (18–64) 7–9 hours; older adults (65+) 7–8 hours. School-age children usually need 9–12 hours. Individual needs vary — the best guide is how rested you feel.
Consistency beats precision
Keeping a steady wake time every day — including weekends where possible — helps anchor your body clock more than chasing a perfect cycle.