REM rebound is the lengthening and increased frequency and depth of REM sleep that occurs following periods of sleep deprivation. When REM sleep is suppressed, the brain compensates — entering REM faster and spending more time in it once sleep is restored. The pressure to recover REM builds in proportion to the deficit.

Accurately measuring REM at population scale matters precisely because of this dynamic. This Sleeptracker-AI study is based on the analysis of more than 4,000,000 nights of sleep.