ðī Sleep Calculator
Find the best time to sleep or wake up
:
How it works
Calculate the best times to go to bed or wake up based on 90-minute sleep cycles. Enter when you need to wake up and get optimal bedtimes, or enter when you're going to sleep and find the best alarm times. Wake up feeling refreshed by timing your sleep cycles perfectly.
Disclaimer: This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.
Frequently Asked Questions
- Why 90-minute sleep cycles?
- Sleep occurs in cycles of roughly 90 minutes, moving through light sleep, deep sleep, and REM sleep. Waking up between cycles (rather than during deep sleep) helps you feel more refreshed. This is why 7.5 hours of sleep can feel better than 8.
- How many sleep cycles do I need?
- Most adults need 4-6 complete cycles (6-9 hours). 5 cycles (7.5 hours) is optimal for most people. Consistently getting fewer than 4 cycles (6 hours) is associated with health risks. Individual needs vary â some people genuinely function well on less.
- What if I can't fall asleep in 15 minutes?
- The 15-minute estimate is an average. If you typically take longer to fall asleep, adjust your bedtime accordingly. If it regularly takes more than 30 minutes, consider improving sleep hygiene: consistent schedule, cool dark room, no screens before bed, and limiting caffeine after noon.