Health
Sleep Calculator
Waking up mid-cycle is why you feel like garbage. Pick when you want to wake up — we'll give you bedtimes that line up with your 90-minute sleep cycles.
FAQ
Why 90 minutes? +
A typical sleep cycle is ~90 minutes — light sleep → deep sleep → REM. Waking at cycle boundaries leaves you alert. Mid-cycle = groggy.
How many cycles? +
Most adults need 5-6 cycles (7.5-9 hours). 4 cycles (6 hours) is the minimum that won't trash your day.