CalculatorsModule / SLEEP-CALCULATOR
Sleep Calculator
Wake up at the end of a cycle — feel refreshed
When do you need to wake up?
Reverse — Going to bed now?
About Sleep Cycles
Sleep cycles are ~90 minuteseach. Waking at the end of a cycleleaves you refreshed. Waking mid-cyclecauses grogginess (sleep inertia).
For best results, aim for 5 or 6 full cycles— that's about 7.5–9 hours. Even 4 cycles (6 hours) works if your schedule is tight.