Sleep Onset Latency Calculator

About this calculator

Sleep onset latency (SOL) is the amount of time it takes to fall asleep after the lights go out, and it is a standard measurement in sleep medicine, recorded in both lab polysomnography studies and consumer sleep trackers that rely on movement (actigraphy) to guess when sleep began. A typical, healthy SOL falls somewhere around 10 to 20 minutes; falling asleep in under 5 minutes can indicate significant sleep deprivation, while a latency that regularly stretches past 30 minutes is one of the diagnostic markers clinicians look at for insomnia.

Sleep researchers and clinicians track SOL over multiple nights rather than judging it from a single data point, since normal night-to-night variation is expected; consumer sleep-tracking apps and wearables surface an SOL estimate to give users a sense of whether their mind is winding down efficiently at bedtime or lying awake much longer than they realize.

Enter the time you turned the lights out and the time you actually fell asleep, and the calculator computes your sleep onset latency and what that duration typically suggests about your sleep.