Wearables and remote monitoring: what the data can and can’t tell us

What wearables actually measure

Most wrist wearables measure heart rate using optical sensors that shine light into the skin and detect changes in blood flow. Many now offer a single-lead ECG feature (touching the crown to record a brief heart trace), estimate blood-oxygen saturation, count steps and estimate sleep stages from movement and heart-rate patterns. Understanding the method matters: an optical estimate of oxygen is not a medical pulse oximeter, and a sleep "score" is an estimate inferred from movement and heart rate, not a clinical sleep study.

Where they genuinely help

The clearest medical benefit so far is in detecting atrial fibrillation. Because AF is often intermittent and silent, a wearable that flags an irregular rhythm — or lets a person capture an ECG during a palpitation — can surface AF that would otherwise be missed, prompting proper assessment. Wearables also encourage activity, help people with long-term conditions engage with their health, and support remote monitoring programmes where clinicians track selected measurements between appointments. Used within a clinical pathway, that data can be valuable.

The limits and pitfalls

The same features can mislead. Consumer sensors are less accurate than medical equipment, especially during movement, in people with darker skin tones for some optical measures, or when worn loosely. False alarms cause anxiety and can drive unnecessary tests; conversely, a "normal" reading can give false reassurance. A wearable ECG records only a single lead and cannot diagnose most heart conditions. And a flood of numbers without context can fuel health anxiety. The data is a prompt to think, not a diagnosis.

Using them sensibly

The sensible approach is to treat wearable data as a useful signal, not a verdict. Trends over time are usually more meaningful than any single reading. An unexpected alert — for instance, a repeated irregular-rhythm notification — is worth discussing with a clinician, who can confirm it properly rather than acting on the device alone. And normal wearable readings should never override how someone actually feels: symptoms matter more than a reassuring number. Framed that way, wearables are a helpful adjunct to care, not a replacement for it.