Sleep Efficiency Calculator

Sleep efficiency is asleep minutes divided by in-bed minutes, and the interesting part is how the numerator gets built. If you leave the tracker field at zero, the page constructs it for you: the minutes taken to fall asleep plus the number of awakenings multiplied by their average length are subtracted from time in bed, with a floor at zero. Type any figure into the tracker field instead and it takes over completely, at which point the latency and awakening fields stop touching the percentage and only feed the onset-latency and WASO rows. That override is worth knowing about before you trust a reading, because nothing reconciles the two: a tracker figure larger than your time in bed will happily produce an efficiency above one hundred percent. On the calculated path, the wakefulness fields carry far more weight per minute than time in bed does.

At the default eight hours in bed, one extra minute spent falling asleep costs about a fifth of a percentage point, while one extra minute in bed adds barely two hundredths — time in bed only looks influential because it is measured in a much larger number of minutes. The rating steps at ninety, eighty-five and eighty percent. Below eighty-five the suggested time in bed switches from simply echoing your current figure to your actual sleep plus fifteen minutes, the core move of sleep restriction therapy, never dropping under five and a half hours. Sleep stages, sleep quality, and whether the awakenings were brief or hour-long are not modelled.