How SleepClock Works
Sleep happens in roughly 90-minute cycles, each moving from light sleep through deep sleep into REM. Waking at the end of a cycle feels natural and alert — waking mid-cycle feels groggy and disorienting.
Fall asleep
Light sleep (N1)
Deep sleep (N2–N3)
REM sleep
Cycle complete (90 min)
Then the cycle repeats — most adults complete 4 to 6 of them per night.
Why 14 minutes?
The average healthy adult takes about 10 to 20 minutes to drift from lying down into actual sleep — a window called sleep onset latency. SleepClock uses 14 minutes as a sensible default, sitting right in the middle of that range. Every calculation adds (or subtracts) that buffer so the cycles you see are genuine sleep time, not time spent staring at the ceiling. If you know you fall asleep faster or slower, mentally adjust by a few minutes either direction.