Sleep Calculator

Calculate the best times to sleep and wake based on sleep cycles. Get optimal wake times or bedtimes to feel refreshed and avoid grogginess.

Sleep Times

Best Bedtime

9:45 PM

6 cycles (9h)

5 cycles (7.5h)11:15 PM
4 cycles (6h)12:45 AM

Adults need 7-9 hours of sleep per night

I want to...

Wake Up Time

:

Recommended Bedtimes

9:45 PM

6 sleep cycles (9 hours of sleep)

Optimal

11:15 PM

5 sleep cycles (7.5 hours of sleep)

Good

12:45 AM

4 sleep cycles (6 hours of sleep)

Minimum

Times include ~15 minutes to fall asleep

Understanding Sleep Cycles

One Sleep Cycle = 90 minutes

  • Stage 1: Light sleep (5-10 min)
  • Stage 2: True sleep (20 min)
  • Stage 3: Deep sleep (20-40 min)
  • REM: Dreaming (10-20 min)

Recommended Cycles by Age

  • Adults: 5-6 cycles (7.5-9 hours)
  • Teens: 6 cycles (9 hours)
  • Children: 7 cycles (10-11 hours)
  • Seniors: 5 cycles (7.5 hours)

Sleep Tips

•Maintain consistent sleep/wake times
•Avoid screens 1 hour before bed
•Keep bedroom cool (65-68°F / 18-20°C)
•Limit caffeine after 2 PM
•Exercise regularly, but not before bed
•Avoid large meals close to bedtime

Sleep Times

Best Bedtime

9:45 PM

6 cycles (9h)

5 cycles (7.5h)11:15 PM
4 cycles (6h)12:45 AM

Adults need 7-9 hours of sleep per night

Frequently Asked Questions

A sleep cycle is approximately 90 minutes long and includes all stages of sleep: light sleep, deep sleep, and REM (dreaming) sleep. Most adults need 5-6 complete cycles (7.5-9 hours) per night. Waking between cycles helps you feel more refreshed.
You likely woke up in the middle of a sleep cycle, especially during deep sleep. Try adjusting your sleep time by 15-30 minutes to wake at the end of a cycle. Using this calculator helps you time your sleep to complete full cycles.
Adults typically need 7-9 hours per night. However, quality matters as much as quantity. 5-6 complete sleep cycles (7.5-9 hours) is optimal. Some people function well on less, but most need at least 7 hours.
On average, it takes 10-20 minutes for healthy adults to fall asleep. This calculator uses 15 minutes as an average. If you consistently fall asleep instantly, you may be sleep-deprived. If it takes over 30 minutes, you may have insomnia.
The best bedtime depends on when you need to wake up. Count back in 90-minute cycles from your wake time, then add 15 minutes to fall asleep. For example, to wake at 7 AM after 6 cycles: 7 AM - 9 hours - 15 min = 9:45 PM.