For how we live.
In a 64-patient randomised trial, home cardiac rehab monitored by a smart ring improved fitness. But both arms wore the ring; what separated them was a weekly call from a clinician.
Contactless photoplethysmography turns an ordinary camera into a heart-rate monitor, and pooled studies show it tracks pulse well. Oxygen, respiration and the stress scores layered on top rest on far thinner evidence.
Green-light pulse sensors raise a real concern about melanin, but independent tests find the skin-tone effect small next to device and movement errors — and the validation studies barely include darker skin.
Head-to-head against an ECG chest strap, popular optical wrist devices differed substantially, and one graded test found a smartwatch running a couple of beats low with a 28-bpm spread in its limits of agreement.
PpgAge predicts chronological age from consumer wearable photoplethysmography and tracks disease. The same optical method has documented accuracy problems across skin tones.