Withings ScanWatch 2 validation studies

A performance validation of six commercial wrist-worn wearable sleep-tracking devices for sleep stage scoring compared to polysomnography

Schyvens et al., 2025 · Sleep Advances

Single most editorially important study in the CircaTest corpus. Six commercial wearables tested against PSG in a uniform protocol means the kappa values are directly comparable in a way most validation studies are not. Drives the head-to-head accuracy figures across CircaTest's comparison content. Limitations: tested previous-generation models (Series 8 not 10, Charge 5 not 6, original ScanWatch not 2) so the results are upper bounds for current models, not direct evidence.