Sleep Cycle Calculator – Find Your Best Bedtime or Wake Time
Based on 90‑minute sleep cycles. Wake up at the end of a cycle – never groggy again. Adjusts for age.
⏰ I want to wake up at
🌙 I want to go to bed at
Why 90‑Minute Sleep Cycles?
Sleep cycles consist of light sleep, deep sleep, and REM. Each cycle lasts about 90 minutes. Waking up in the middle of a cycle causes grogginess (sleep inertia). This calculator suggests bedtimes or wake times that align with cycle endings, so you feel refreshed.
Age affects total sleep need: teens need 8‑10 hours, adults 7‑9, seniors 7‑8. Our recommendations adjust automatically.
FAQs
How accurate is this?
Very accurate for most people. Individual variations exist, but it's a proven method to reduce morning grogginess.
What about sleep onset time?
Most people fall asleep within 15 minutes. The calculator assumes you fall asleep quickly. Add 15‑20 minutes to bedtime if you take longer.
Is my data stored?
No – all processing is local.