Recommended bedtimes by sleep cycle
Bedtimes are reversed from your wake time (wake − cycles × 90 min − 15 min latency). Lie down about 15 minutes before the listed time so you can fall asleep. Times marked “previous day” fall before midnight.
| Cycles | Sleep duration | Bed time |
|---|
Understanding sleep latency — the 15-minute rule
You rarely fall asleep the moment your head hits the pillow. The gap between lying down and actually drifting off is called sleep latency. For a healthy sleeper it is usually 10 to 20 minutes, which is why this calculator builds in a 15-minute cushion before your first sleep cycle begins.
That cushion matters because the 90-minute cycle only starts once you are asleep. If you ignore it and climb into bed exactly 7.5 hours before your alarm, you will actually sleep less than five full cycles, and your alarm could land in deep sleep — the recipe for a groggy morning.
A very short sleep latency (dozing off in under 5 minutes) can be a sign of sleep deprivation, while a very long one (30+ minutes) can signal stress, caffeine too late in the day, or too much evening light. If falling asleep is a struggle, try a consistent wind-down routine, keep your bedroom cool and dark, and avoid screens in the last hour before bed.
Need the opposite direction? Use the wake-up times calculator, or try the main calculator for both in one place.