Window
14 nights
Long enough to show a real pattern, short enough to reflect your current life.
Feature
The sleep ledger
One bad night is noise. A fortnight of them is the reason your recovery score has been flat for a week, and it is the thing a single sleep score never shows you.
The sleep ledger tracks two numbers most sleep screens omit: a rolling 14-night debt balance, where nights short of your need add in full and surplus nights repay at half rate, and a circadian regularity score from 0 to 100 derived from how much your bedtime and wake time drift night to night. It also reports social jet lag, the gap between your weekend and weekday mid-sleep.
Repayment
Half rate
Banking sleep works, but not hour for hour. Surplus is credited conservatively.
Regularity
0–100
100 means the same bedtime and wake time every night. Under 60 means your schedule is drifting.
Why a balance beats a nightly score
A nightly sleep score answers one question: how was last night? It is a fine question, and it is not the one that explains a flat week.
Sleep loss accumulates. Five nights an hour short is five hours down, and the consequences, blunted training adaptation, worse glucose handling, poor concentration, show up gradually enough that people rarely connect them to the cause. Worse, subjective sleepiness plateaus after a few days of restriction, so you stop feeling proportionally worse while measured performance keeps declining.
A running balance makes the accumulation visible. It also makes the repayment realistic: the ledger will tell you roughly how many nights of sleeping an hour past your need it would take to clear, which is usually a longer and more sobering number than people expect.
Why surplus repays at half rate
If shortfalls counted in full and surplus counted in full, a single ten-hour Saturday would erase a week of deprivation. The evidence does not support that.
Extended recovery sleep restores alertness substantially and repays part of the deficit, but several measures tied to metabolic and cognitive function do not fully normalise after one long night. Crediting surplus at half value is a deliberately conservative model: it acknowledges that catch-up sleep genuinely helps, without pretending the debt is refundable on demand.
The balance is also floored at zero, because you cannot meaningfully bank sleep in advance of a hard week.
Regularity is the half everyone ignores
Two people both average seven and a half hours. One goes to bed within twenty minutes of the same time every night. The other varies by two hours depending on the day. They do not get the same outcome.
Consistency of sleep timing predicts several health and performance measures about as well as duration does. A stable schedule keeps your circadian system aligned, which improves sleep efficiency and how easily you fall asleep in the first place.
The ledger scores this directly from your measured bed and wake times, reports the drift in minutes, and separately reports social jet lag: how much later your mid-sleep runs at weekends than on weekdays. An hour or more is the point at which it starts behaving like genuine travel across time zones, every single week.
You can try the same debt arithmetic without the app using our free sleep debt calculator.
Common questions
How does Apex Health: Recovery Coach know my sleep need?
It starts from a baseline need and personalises it using your own history and current sleep debt, and the same figure is shared with the Sleep Coach and the dashboard sleep score so all three agree. Importantly, the debt itself is measured against the stable baseline need rather than the debt-adjusted figure, so the two cannot feed into each other and ratchet upward.
What counts as a bad regularity score?
Below about 60 out of 100 indicates your bedtime and wake time are drifting enough to matter, typically more than half an hour of variation night to night. Above 80 is very regular. The score is most useful as a trend: a steady decline over a fortnight usually has an identifiable cause, such as a new work pattern or a run of late nights.
Does it count naps?
The ledger reads the sleep Apple Health records, which includes naps your watch detects. Naps contribute real recovery, though a long or late nap reduces night-time sleep pressure and can push your bedtime later, which risks deepening the underlying deficit rather than repaying it.
Wake up to a verdict, not a spreadsheet.
Apex Health: Recovery Coach turns the Apple Health data you already generate into one clear decision each morning. Free, private, and entirely on your device.
Apex Health: Recovery Coach provides general wellness and fitness information computed from your own data. It is not a medical device and does not diagnose, treat, or prevent any condition. Always consult a qualified professional for medical concerns.