Sleep Calculator
Find optimal bedtimes and wake times based on 90-minute sleep cycles.
Enter when you need to wake up or when you want to go to bed.
Optimal Sleep Times
Sleep cycles last approximately 90 minutes each. Waking up between cycles (rather than in the middle of one) helps you feel more rested and alert.
How it works:
- It takes the average person about 15 minutes to fall asleep
- Each complete sleep cycle is ~90 minutes
- Adults should aim for 5–6 complete cycles (7.5–9 hours)
Bedtime = Wake Time − (Cycles × 90 min) − 15 min fall-asleep time
Recommended sleep by age:
- Teenagers (14–17): 8–10 hours
- Adults (18–64): 7–9 hours
- Older adults (65+): 7–8 hours
Tips for better sleep:
- Keep a consistent sleep schedule, even on weekends
- Avoid screens 30–60 minutes before bed
- Keep the room cool (65–68°F / 18–20°C), dark, and quiet