Most people wearing a smartwatch think of it as a fitness gadget that counts steps and reminds them to stand up. That picture is now seriously out of date. Today’s wearables can detect heart arrhythmias, monitor blood oxygen, alert caregivers during a seizure, and even catch a fall and call emergency services. The question isn’t whether these devices do impressive things. It’s whether they do those things reliably enough to matter for your health.
What Wearables Are Actually Good At
The strongest case for wearable health tech is continuous cardiac monitoring. Atrial fibrillation often causes no symptoms at all, so catching it passively, while someone is just going about their day, has genuine clinical value. The Apple Watch ECG feature received FDA clearance back in 2018, and since then multiple peer-reviewed studies have confirmed it can identify AFib with clinically meaningful accuracy when used correctly.
Epilepsy monitoring is another area where wearables have moved from consumer toy to medical tool. Several companies are now developing Apple watch seizure detection capabilities, turning it into a proper ecosystem of tools. EpiWatch, a Johns Hopkins Medicine spinout, received FDA 510(k) premarket clearance for its seizure detection platform, reporting 98% sensitivity for tonic-clonic seizures with a false alarm rate of just 0.08 per day. Apps like EpiCentr take a broader approach, pairing with Apple Watch to monitor for seizure motion patterns, abnormal heart rates, and unusual falls, then sending GPS-tagged alerts to emergency contacts if something is detected. For a family managing epilepsy, having practical options is already a significant shift from where things stood just a few years ago.
Sleep tracking has also matured considerably. Devices like the Oura Ring have been evaluated against medical-grade actigraphy in published research, with reasonably strong agreement on total sleep time and other core metrics. That doesn’t make a ring a clinical sleep study, but it does mean the data is genuinely useful, not just decorative.
Where the Limits Are
Understanding what wearables can’t do is just as important as knowing what they can. The gap between consumer and clinical devices is real, even if it’s shrinking.
Two smartwatches measuring the same person’s heart rate variability may give different results, and neither figure may match what a hospital monitor would show. Variability in measurement methods across devices complicates how this data can be used, and manufacturers don’t always make their algorithms easy to compare or audit.
There are several categories where even the most enthusiastic users should keep their expectations grounded:
- Blood glucose monitoring on consumer wearables remains unreliable. The FDA issued a specific safety communication in February 2024 advising people not to use smartwatches or smart rings to measure blood glucose levels. Continuous glucose monitors like the Dexcom G7 work accurately, but they use a subcutaneous sensor, not an optical wrist sensor.
- Most seizure detection wearables only identify one seizure type. EpiWatch, for example, is FDA-cleared specifically for tonic-clonic (grand mal) seizures. Other non-convulsive seizure types cannot currently be detected by the device, which is something anyone considering it for a loved one needs to know upfront.
- Consumer wearables are not a substitute for clinical evaluation. Readings from a smartwatch ECG can flag something worth investigating, but they cannot diagnose or rule out a condition. A doctor still needs to interpret the data in context.
The Regulation Gap and Why It Matters
Not all “health features” on consumer devices go through the same level of scrutiny. Consumer wearables marketed for general wellness and fitness may not need regulatory approval if they avoid specific medical claims. That means some features marketed as “health monitoring” are closer to informed guesses than validated measurements.
The distinction matters practically. When a device is FDA-cleared, there’s a defined process behind it, involving a premarket submission and a review of effectiveness and safety risks before the product can be sold. Algorithms used in cleared devices are typically trained on large clinical datasets and tested against standards like hospital EEG or Holter monitoring. Algorithms in non-cleared devices may not be.
This creates a tiered landscape that’s worth understanding before buying:
- Cleared medical-grade wearables, such as the Empatica Embrace (also FDA-cleared for seizure detection) or the KardiaMobile 6L cardiac monitor, are validated for specific conditions and designed to produce data doctors will actually use.
- Consumer smartwatches with some FDA-cleared features, like the Apple Watch ECG or its sleep apnea detection on Series 10, occupy a middle ground. The cleared feature is validated; other health metrics on the same device may not be.
- General wellness trackers offer trend data and broad patterns, useful for motivation and awareness, but not appropriate for making medical decisions.
Making Sense of Your Data
Even when a device works as intended, the data only helps if you know how to read it. A heart rate spike during a stressful meeting is not a cardiac event. A sleep score of 68 is not a diagnosis. Consumer devices often strip away context in favour of clean dashboards, which can make normal variation look alarming, and genuine patterns easy to dismiss.
The most useful thing a wearable can do is help you notice something worth discussing with a doctor, not replace that conversation. If your device flags an irregular heart rhythm or a persistent dip in blood oxygen over several nights, that’s worth a call to your GP. Acting on a single anomalous reading, or ignoring a consistent one, are both ways to misuse the technology.
The best wearable is the one matched to an actual need, used by someone who understands what the numbers mean and what they don’t.
