睡眠債：它是什麼，以及如何追蹤

Sleep debt is the cumulative difference between the sleep you need and the sleep you actually get. If your body needs about eight hours and you sleep six, you add roughly two hours to the running deficit that night. Do that across several nights and the shortfall stacks up, which is why a few bad nights in a row feel heavier than any one of them alone.

Partially, and mostly through consistency rather than one big sleep-in. A few nights of fuller, regular sleep can repay recent debt and lift how you feel and perform. But research suggests that catching up over a single weekend does not fully reverse the effects of a week of short sleep, especially on attention and metabolic markers. The reliable fix is sustained, adequate nightly sleep, not occasional overcompensation.

There is no single hard threshold, but the pattern matters more than the number. Studies show measurable declines in attention and reaction time building within about a week of losing even one to two hours a night. A small, occasional deficit that you repay quickly is normal life. A deficit that keeps growing week over week is the one worth taking seriously, because chronic shortfall is what affects mood, metabolism, and performance.

Only up to a point. Sleeping longer on the weekend can ease some of the grogginess from a short week, but it does not undo all of it, and large swings in sleep timing can confuse your internal clock and make Sunday night harder. Some research has linked weekend catch-up patterns to worse metabolic outcomes than steady sleep. Treat catch-up as partial relief, not a reset button.

Take your personal sleep need, subtract what you actually slept, and add the difference to a running total over a window of days. A common approach uses a rolling window of about 14 days so the figure reflects a real trend instead of one rough night. Wellness Project does this automatically from the sleep your devices already record, so you see a single rolling deficit rather than a tangle of nightly durations.