Vitality Tracker Sleep Scoring Methodology, Open Specification v2.0.1, public edition

Open specification of the Sleep Health Index, the sleep score used by Vitality Tracker. The index is a rolling 28-night composite of five components weighted by evidence grade and effect size: sleep regularity (35%), duration (30%), continuity (15%), circadian alignment (10%) and restoration (10%). Sleep stages are displayed but carry no weight. The specification sets out every weight, curve, age band and threshold; a measurement-provenance model with three-tier handling of consumer-wearable continuity data, including a device bias table derived from published polysomnography validations; the coverage rule for missing data, with no redistribution of missing weight; the versioning policy; and the external review of version 1.1.0 by an independent data scientist, with the changes it produced and the three recommendations declined. Version 2.0.1 is the public edition of v2.0.0 (13 July 2026): editorial corrections only, with no change to any output. The Sleep Health Index describes a sleep pattern for general wellness; it is not a medical device, is not diagnostic, and has not been validated against health outcomes.