How EveryBand calculates Sleep

EveryBand Sleep combines four available factors: sleep duration against estimated need, clock-time regularity, efficiency and high sleep stress. It is an independent wellness score. A stage chart, time in bed and a headline score describe different aspects of the night.

This page describes the documented implementation reviewed on 15 October 2026. Your installed beta can differ. Strap model, firmware, Health permissions and retained coverage affect which measurements and estimates are available. Sleep estimates are not a diagnosis or a substitute for a sleep study.

Supported strap paths use available heart-rate, motion and sleep-state context to select and refine sleep windows. Some paths infer the window from qualified observations and keep that inference explicit. Recorded Apple Health sleep can provide available context when the relevant category is read and local data does not already own it.

Time in bed can include awake periods. The app resolves overlapping Health sleep records rather than adding every in-bed, awake and asleep interval together. Missing stages are not invented. A main sleep and a nap can both exist without a nap replacing the overnight summary.

Wrist activity is an established input to sleep/wake estimation; Cole and colleagues' study is background for that approach. EveryBand's heuristic estimator is independently written. The paper does not establish the accuracy of EveryBand's sleep windows or stages.

When a scored factor is unavailable, the remaining weights are normalized. Missing consistency is not treated as zero. A Sleep score requires recorded sleep duration; other available factors refine it.

Restorative balance, heart-rate dip and continuity may be useful details, but they have no direct headline Sleep weight in this version. Detailed stage minutes therefore should not be read as a separate formula for recreating the score.

The current calculation begins with an eight-hour software baseline. It adds carried sleep debt and an adjustment for the preceding day's higher Strain. The result is bounded between four and eleven hours in the calculation; those bounds are not personal sleep recommendations.

Debt considers the preceding four days with decreasing weights of 1, 0.5, 0.25 and 0.125, capped at two added hours. Up to two hours of a prior day's nap can offset that day's shortfall. A later nap does not retroactively rewrite the completed overnight score on the day of the nap. The recent-load adjustment can add up to one hour.

Consistency needs at least two prior main-sleep intervals. It compares sleep/wake clock-minute patterns over a full day, so schedule changes can affect it. High sleep stress contributes only when its covered duration reaches the smaller of 30 minutes or half the sleep interval. These are explicit software rules, not proof of each person's physiological sleep requirement.

The native stage estimator uses 30-second epochs with five-minute feature context, then applies smoothing and boundary rules. Available motion and cardiac contrast help distinguish awake, core, deep and REM-like context. Some supported inferred paths also exclude sustained, directly observed interior waking from the duration asleep.

When the required contrast is absent, the app can retain unspecified sleep instead of fabricating a detailed stage. A wrist sensor does not observe brain waves. Quiet waking, movement, fit and incomplete observations can affect both stage labels and boundaries. A detailed-looking chart does not make the result equivalent to polysomnography.

An unfinished window, incomplete sync, unavailable Health category or insufficient supported observations can leave some or all of the night unavailable. Device connection and Health export status are separate from the evidence needed to close and score a sleep.

Check Health source and sync behavior, and keep model/firmware limits in view on compatibility. Do not assume a missing night means zero sleep or that buying Full repairs missing records. Algorithm updates can change estimates, so comparisons across versions need care.

EveryBand is independent and is not affiliated with, endorsed by or sponsored by WHOOP or Apple. Their names identify compatible hardware and data services.

Written by EveryBand. Published October 16, 2026; reviewed October 16, 2026. Product descriptions are subject to the installed build; third-party features and terms may change.

• Cole et al.: Automatic sleep/wake identification from wrist activity

EveryBand is an independent app and is not affiliated with, endorsed by, or sponsored by WHOOP, Apple, or Bevel. Third-party product names and trademarks belong to their respective owners and are used only for factual compatibility and interoperability descriptions.

Other app and device names belong to their owners. EveryBand is also independent of Sixteen and its publisher. For corrections, contact EveryBand.

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