# Wearables & tracking: what the research actually says

What your tracker measures well (total sleep time), what it measures badly (stages), and what it invents (sleep scores).



## All studies

- **Performance of seven consumer sleep-tracking devices compared with polysomnography** — Chinoy ED, Cuellar JA, Huwa KE, et al. (2021), Sleep 44(5):zsaa291. Consumer devices estimated total sleep well but were poor at sleep stages — trust duration, not deep/REM.

- **Wearable sleep technology in clinical and research settings** — de Zambotti M, Cellini N, Goldstone A, Colrain IM, Baker FC (2019), Medicine & Science in Sports & Exercise 51(7):1538–1557. Review of what wearables can and cannot measure; stage classification and 'sleep scores' lack validation.

- **Orthosomnia: are some patients taking the quantified self too far?** — Baron KG, Abbott S, Jao N, Manalo N, Mullen R (2017), Journal of Clinical Sleep Medicine 13(2):351–354. Case series of people whose fixation on tracker data worsened their sleep — Galpin's health-anxiety warning has a name.

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Educational summary of published research, not medical advice. Screening scores are not diagnoses. If a score is elevated or you feel unwell, talk to a clinician.

SleepShred for iPhone: https://apps.apple.com/app/id6802040541