Your need tonight, not a flat eight hours.
A 7:45 base is the floor, not the answer. Yesterday's training load, how run down you told it you feel, and a rolling debt term all stack on top of it — capped, never unlimited, but real.
The score has four parts
Duration, efficiency, consistency and timing, each weighted and renormalised over whatever your night actually measured — an unmeasured component is left out of the formula, not silently scored as a zero that drags the total down.
Duration is penalised both ways
Too short costs you, and there's a ceiling on how much good efficiency can rescue a five-hour night. A great efficiency percentage on not enough sleep is still not enough sleep.
Debt accumulates on a real window
A 14-night rolling ledger, not a single bad night forgotten by morning. Repayment adds minutes to tonight's need until the debt actually clears.
A drift flag, not just a number
When resting heart rate or breathing rate has moved off your own baseline, the app says so directly rather than burying it inside one composite score.
Training and how you're feeling both move tonight's number.
Fitness → Sleep
A hard session logged in Fitness raises tonight's need directly — the debt formula reads your real training load, not a guess.
Recovery → Sleep
Recovery's own confidence label (solid, fair, rough, or no data) is visible from the same screen, so a low sleep score and a low-confidence recovery reading are never confused for the same problem.