Resources

Where we actually go for primary information about wearable health. We make these public because it's how we'd want a site to source its work, and so you can check up on ours.

FDA and CPSC

• FDA 510(k) database — lookup for ECG, SpO2, and other clinical-feature clearances. Search by manufacturer (Apple, Fitbit, Withings).
• CPSC recalls and Health Canada recalls — official recall databases for wearable safety checks.
• Wayback Machine — we use this constantly to verify manufacturer claims that have since been edited.

Validation literature

A short list of peer-reviewed papers we cite often when assessing wearable accuracy.

• Bent et al. (2020). "Investigating sources of inaccuracy in wearable optical heart rate sensors." npj Digital Medicine 3:18.
• Chinoy et al. (2021). "Performance of seven consumer sleep-tracking devices compared with polysomnography." Sleep 44(5).
• Hermand et al. (2019). "Validation of a photoplethysmographic heart rate monitor: Polar OH1." International Journal of Sports Medicine.
• de Zambotti et al. (2020). "The boom in wearable technology." Sleep 43(4).

Where a study contradicts a manufacturer claim, we'll cite the study by name and link to the abstract.

Manufacturer documentation

• Fitbit safety and care guide
• Garmin support center
• Apple Health and Activity
• Withings support
• Oura support

Tools we use

• A reference chest-strap heart-rate monitor (Polar H10) for accuracy comparisons.
• A fingertip pulse oximeter (Masimo MightySat) for SpO2 comparisons at rest.
• Keepa for Amazon price history.
• FCC ID search for radio certifications and internal photographs of new devices.