Shift Recovery Score:
how it is calculated.
AfterShift scores your sleep against your shifts, not a 9-to-5 day. This page lists every published input, weight, and threshold behind its scores: the Shift Recovery Score, the Sleep Score, Readiness, the sleep debt trend, and the recovery load. It also says plainly what these numbers are not.
What the scores are and are not
What they are
- Custom heuristics built for people who sleep around shifts, with the score weights and Readiness thresholds published on this page
- Shift-aware: Readiness, sleep debt, and the Recovery Timeline are measured over the window between your previous shift's end and your next shift's start, not midnight to midnight
- Personal: Readiness compares your sleep with the sleep target you set, not with other people
- Mostly Premium: the Shift Recovery Score, Sleep Score, and Readiness are part of AfterShift Premium; the sleep debt trend and recovery load are free
- Informational: they help you make a decision and leave the decision to you
What they are not
- Not clinically validated; they are custom heuristics, and no validation study backs them
- Not a medical assessment, and not a diagnosis of Shift Work Disorder or any other condition
- Not a replacement for a clinical sleep evaluation if your sleep is badly impaired
- Not based on heart rate or heart-rate variability; AfterShift reads only sleep data from Apple Health
- Not benchmarked against other users
The scores, input by input
These are the weights and thresholds the app uses today. The recovery load is described by its inputs and bands; its internal weights are heuristics and are not published.
01
Shift Recovery Score (Premium)
A 0 to 100 score for one sleep, shown on that sleep's Recovery details (tap a sleep in the Sleep tab, or "View Recovery Details" on Today). Three inputs, weighted: sleep duration 50%, sleep continuity 30%, and sleep stages 20%.
02
Sleep Score (Premium)
A 0 to 100 score for your latest main sleep, with a history chart, on the Today tab and in Recovery details. Four inputs, weighted: duration 40%, sleep efficiency 20%, continuity 20%, and stages 20%.
03
Readiness (Premium)
The rating that answers "am I ready for my next shift?" AfterShift adds up the sleep you got in the window between your previous shift and your next one, naps included, and divides it by your sleep target. Below 0.6 of your target is Low, below 0.9 is OK, and 0.9 or more is Good. Readiness comes with a short reason and, when it applies, an on-call note. It shows on Today, on the Readiness widget, and through Siri.
04
Sleep debt trend (free)
A smoothed line of your sleep debt per cycle between shifts, shown once there are at least three points. It reads Building, Stable, or Recovering, depending on whether debt moved by half an hour over the last three cycles. Weeks with on-call time get a badge.
05
Recovery load (free)
A 0 to 100 load score in the Recovery plan: Low is 0 to 30, Moderate is 31 to 60, and High is 61 to 100. It draws on your sleep debt, consecutive shifts, recent night shifts, how much you rely on naps, and late caffeine, using the last 14 days of sleep and caffeine and the last 30 days of shifts. A "What's driving this" breakdown shows the factors behind the number, and two or three suggested techniques follow. The app labels them "Suggestions, not prescriptions."
Where the data comes from, and what happens when it is missing
Sleep comes from Apple Health
- AfterShift reads sleep from Apple Health, read-only. An iPhone on its own records no sleep, so you need an Apple Watch or another app that saves sleep to Health
- Naps you log in AfterShift, or start with the nap timer, appear alongside the sleep imported from Health
- Your shifts come from your roster: a repeating rotation, shifts you add, or shifts imported from your calendar
Missing stage data
- If your tracker records how long you slept but not sleep stages, the stage input gets a neutral default
- That keeps a sleep from being marked down for data that was never recorded
- It also means a score can look decent without stage data. Read it with that in mind
How the weights were chosen
There is no agreed formula for scoring recovery from sleep. The weights on this page are design choices made for shift work, and none of them has been clinically validated. We publish them so you can judge the numbers for yourself.
For the science of shift-work sleep, two good starting points are the U.S. NIOSH shift work training module and the AASM entry on the International Classification of Sleep Disorders, which covers Shift Work Disorder. Both are written for clinicians, and both are readable.
How to use the scores, and how not to
Use them to inform a decision
- Decide whether to take a nap before your next shift
- See whether sleep debt is building across a run of shifts
- Check what is driving a high recovery load, and pick something to try
- Take a 14-day sleep report to your GP or occupational health, instead of a vague "I feel tired"
Do not use them to
- Diagnose a sleep disorder; see a sleep specialist if your sleep is badly impaired
- Decide whether you are safe to drive after a shift. That is a yes-or-no safety judgement, and no score can make it
- Expect to never feel tired; shift work has real biological costs that no app removes
- Compare yourself with other people; the scores are about your own sleep
FAQ
How is the AfterShift Shift Recovery Score calculated?
It is a 0 to 100 score for one sleep, built from three weighted inputs: sleep duration (50%), sleep continuity (30%), and sleep stages (20%). You find it on the Recovery details of each sleep in the Sleep tab. It is part of AfterShift Premium.
What is the difference between the Shift Recovery Score and Readiness?
The Shift Recovery Score rates a single sleep. Readiness looks ahead to your next shift: it compares the sleep you got in the window between your previous shift and your next one, naps included, with your sleep target, and shows Low, OK, or Good. Both are Premium.
Are the AfterShift scores clinically validated?
No. The Shift Recovery Score, Sleep Score, Readiness, sleep debt, and recovery load are custom heuristics designed for shift workers. They have not been clinically validated, they are not medical advice, and they do not diagnose Shift Work Disorder or any other condition.
Which parts of AfterShift are free?
Sleep Timing, the Sleep Stages breakdown, the Recovery Timeline, the sleep debt trend line, and the Recovery plan with its load score are free. The Shift Recovery Score, Sleep Score, Readiness, Sleep Continuity, nap and caffeine detail, and Trends are part of Premium.
What happens if my tracker does not record sleep stages?
The stage input gets a neutral default, so a sleep is not marked down for data your tracker never recorded. The flip side is that a score can look decent without stage data. AfterShift reads sleep from Apple Health, so it needs an Apple Watch or another app that saves sleep to Health; an iPhone on its own records no sleep.
Open AfterShift.
Sleep and recovery tracking built around your shift roster instead of a 9-to-5 clock. Start free; the scores on this page come with Premium. Your data stays on your iPhone.