how the readiness score works

The number itself is less important than the sentence RestUp puts next to it. A score of 76 reads as “your body is ready for a steady day”. A 52 reads as “your body is asking for rest today”. The bands are listed further down.

Readiness is a weighted blend of five components. The weights add up to 100 and describe how much each part can contribute at most.

Sleep balance (up to 25)

Your average nightly shortfall over the last seven recorded nights against your sleep target, which is eight hours unless you change it in your profile. Here a long night offsets a short one in full, so this is a close cousin of the sleep debt ledger rather than the same arithmetic: the ledger repays surplus at a quarter rate and never goes below zero, while this average does neither. No average shortfall earns the full 25. Up to half an hour a night earns 85 percent of it, up to an hour 60 percent, and up to an hour and a half 35 percent. Beyond that it drops below a fifth and reaches zero at three hours a night.

Recovery (up to 25)

An average of up to four signals from last night: resting heart rate against your 14-day average (lower than usual is good), overnight heart rate variability against your 14-day average (higher than usual is good), sleep efficiency (the share of time in bed you actually spent asleep, with 90 percent or better earning full marks), and the direction your resting heart rate has been drifting over the past week. The component is the plain average of whichever of those signals your watch recorded.

Each signal moves in simple steps. Resting heart rate three or more beats below your average earns full marks, anything up to your average 80 percent, up to three beats above half, up to six above a fifth, and more than that nothing. Heart rate variability five or more milliseconds above your average earns full marks, at or above it 80 percent, up to five below half, up to ten below a fifth, and further below nothing. Sleep efficiency of 90 percent earns full marks, 85 percent earns 80, 75 percent earns half, and anything lower a fifth. A resting heart rate falling by more than about a third of a beat a night over the week earns full marks for the trend.

The HRV steps are in milliseconds of whichever measure your phone provides, SDNN on iPhone or RMSSD on Android. The two sit at different typical values, so the steps are not exactly the same size on both platforms; the percentage-based nervous-system component below does not have that quirk.

Training load (up to 20)

The ratio of your recent activity to your longer-run activity, sometimes called an acute-to-chronic ratio. Training a little more than usual is fine and scores fully. A sharp spike, or a long stretch of doing much less than usual, both lower the score, because both mean the week is out of step with what your body is used to. In numbers: a ratio between 0.8 and 1.3 earns the full 20, 0.6 to 0.8 earns 70 percent, 1.3 to 1.5 earns 60 percent, and below 0.6 earns 40 percent. Above 1.5 the score falls from 40 percent and reaches zero at a ratio of 2.5.

Nervous-system balance (up to 20)

Last night’s heart rate variability as a fraction of your 14-day average. Ten percent or more above it earns the full 20; at or above your average, 80 percent; up to 10 percent below, 60 percent; up to 20 percent below, 35 percent; further below, 10 percent. A rising or falling seven-day trend then adds or removes up to a tenth of the component. See HRV against your own baseline.

Consistency (up to 10)

Your sleep regularity index, a measure of how similar your bedtimes and wake times are from one day to the next, on a scale where 100 means identical days. An index of 85 or higher earns the full 10; below that the points scale down in a straight line.

If your watch did not record a signal, that component is removed from both the top and the bottom of the fraction before the score is scaled to 100. A night with no heart data is scored on what was recorded, and RestUp shows you how complete the reading is rather than filling the gap with an assumption.

Nights you add or edit by hand count towards your rhythm and your sleep history, but they never feed the scores, because they carry no heart signals.

• 85 and above: “your body is ready for a big day”. Strong recovery.
• 70 to 84: “your body is ready for a steady day”. Recovering well.
• 55 to 69: “a gentler day would serve you well”. Steady.
• Below 55: “your body is asking for rest today”. Take it easy.

For your first seven nights the app says so plainly: “RestUp is learning your rhythm”. Baselines settle over roughly two weeks, so early readings lean on fewer nights and are labelled as such.

Wrist temperature, blood oxygen and breathing rate are shown on the Sleep screen on nights your watch records them, compared with your own recent median, but they are display-only. They never move the readiness score. Mood check-ins are recorded alongside the score, not blended into it.

The components follow published findings rather than a proprietary black box. The weights and step sizes are RestUp’s own choices; the studies are why each component is there at all.

• Sleep restriction has costs that accumulate across days: Banks and Dinges, 2007, Journal of Clinical Sleep Medicine.
• Heart rate variability is best read against an athlete’s own rolling average rather than a single day or a population norm: Plews and colleagues, 2013, Sports Medicine. Resting and recovery heart rate measures are reviewed alongside it in Buchheit, 2014, Frontiers in Physiology.
• Rapid increases in training load relative to the recent norm are linked with higher injury risk in athletes: Gabbett, 2016, British Journal of Sports Medicine.
• In about 61,000 UK Biobank participants, sleep regularity predicted mortality more strongly than sleep duration did: Windred and colleagues, 2024, SLEEP.

None of this makes the score a diagnosis. RestUp is a wellness companion, not a medical device. If a low reading persists or you feel unwell, talk to a doctor, not an app.