Sleep Calculator
Find bedtimes or wake-up times that line up with complete 90-minute sleep cycles.
How it works
Sleep runs in cycles of roughly 90 minutes. Waking at the end of a cycle, rather than in the middle of deep sleep, may help you feel less groggy. This calculator allows about 15 minutes to fall asleep and suggests times for 4–6 full cycles.
Most adults need 7 or more hours of sleep a night, which is usually 5 cycles. Cycle length varies between people, so treat the times as a guide.
Medically reviewed by Lena Hartmann, PhDUpdated on
Sources
- Watson NF, et al. (2015). Recommended Amount of Sleep for a Healthy Adult. Journal of Clinical Sleep Medicine. https://doi.org/10.5664/jcsm.4758