Sleep Cycle Calculator
Find the optimal bedtime or wake time based on 90-minute sleep cycles.
Wake up feeling refreshed by timing your sleep correctly.
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Optimal Sleep Times
Sleep occurs in cycles of approximately 90 minutes. Each cycle moves through light sleep, deep sleep, and REM sleep. Waking up between cycles (rather than in the middle of one) helps you feel more refreshed.
Key formula:
Wake Time = Bedtime + (90 minutes × Number of Cycles) + 15 minutes to fall asleep
Sleep cycle structure:
- Stage 1 (Light sleep): 5–10 minutes
- Stage 2 (Deeper sleep): 20 minutes
- Stage 3 (Deep/slow-wave sleep): 20–40 minutes
- REM sleep: 10–60 minutes (increases with each cycle)
Recommended cycles by age group:
- Adults (18–64): 5–6 cycles (7.5–9 hours)
- Teens (14–17): 6 cycles (8–10 hours)
- Seniors (65+): 5 cycles (7–8 hours)
How to use this calculator:
- Enter your desired wake time OR bedtime
- The calculator shows optimal times based on complete sleep cycles
- It accounts for the average 15 minutes it takes to fall asleep
Tips for better sleep:
- Keep a consistent sleep schedule
- Avoid screens 30–60 minutes before bed
- Keep your bedroom cool (60–67°F / 15–19°C)
- Avoid caffeine 6+ hours before bedtime