Wearable Technology: Your Health on Your Wrist

Not long ago, tracking your health meant a trip to the doctor’s office, a blood pressure cuff, and a clipboard of questions that tried — imperfectly — to capture what your body had been doing for the past year. That world is changing, fast. Today, a device no larger than a watch can continuously monitor your heart rate, your sleep, your stress, your blood oxygen, and the number of steps you have taken — all while you go about your day without giving it a second thought.

Wearable technology has moved from counting steps to measuring health in ways that would have seemed like science fiction a generation ago. As a sports and lifestyle medicine physician, I find this genuinely exciting. We have always known that lifestyle behaviors — how you move, how you sleep, what you eat, how you manage stress — have the greatest impact on health. What wearables give us, for the first time, is a real-time window into those behaviors. Not what you think you did last Tuesday, but what actually happened.

This article is the first in a series designed to help you understand wearable technology, what it can and cannot do, and how to use it as a tool — not a source of anxiety — in service of your health.

What Is a Wearable Health Device?

A wearable health device is any electronic device worn on the body that continuously or periodically monitors physiological signals or behaviors. The most common form is the wrist-worn smartwatch or fitness tracker, but the category also includes smart rings, chest straps, adhesive patches, continuous glucose monitors, and even smart clothing. What they all share is the ability to passively collect data about your body without requiring you to do anything except wear them.

What Can They Measure?

Modern wearables measure far more than most people realize. Here is a look at what is currently available in consumer devices:

1. Heart rate – Continuous measurement using light-based sensors on the skin. This is the foundation of nearly every health wearable.

2. Heart rate variability (HRV) – The tiny variations in time between heartbeats. This is one of the best indicators of how well your nervous system is recovering from stress, whether physical, emotional, or illness-related.

3. Blood oxygen (SpO2) – The percentage of oxygen your red blood cells are carrying. Useful for tracking respiratory health and detecting early signs of illness.

4. Sleep – Most wearables can now estimate how long you slept and break it into stages: light, deep, and REM. This gives you a picture of sleep quality, not just quantity.

5. Physical activity – Steps, active minutes, calories burned, exercise type, and workout load.

6. Skin temperature – Small deviations from your personal baseline can signal illness, menstrual cycle changes, or poor recovery.

7. Stress – Using HRV and skin conductance, some devices estimate your physiological stress load throughout the day.

8. Glucose (via continuous glucose monitors or CGMs) – Devices like the Dexcom G7 measure blood sugar continuously, without fingersticks.

What They Cannot Do — Yet

As impressive as these devices have become, it is important to be clear about their limitations. Consumer wearables are not medical diagnostic devices (with a few exceptions, such as the Apple Watch’s FDA-cleared ECG for detecting atrial fibrillation). The optical sensors that measure heart rate and blood oxygen are estimates. They can be thrown off by movement, skin tone, and device fit. Sleep staging is approximately 70–80% accurate compared to laboratory sleep studies. Think of a wearable as a very good mirror, not a medical test. It shows you trends over time — and those trends are genuinely valuable. But a single data point on any given morning is just that: a single point. The real insight comes from watching how your metrics shift over days, weeks, and months in response to your choices.

The Big Idea: From Episodic to Continuous 

Here is what I find most compelling about wearable technology from a medical standpoint. The traditional model of healthcare is episodic — you come in for an appointment, your vital signs are taken as a snapshot of your health that day, and we make decisions based on that snapshot. The problem is that your health is not episodic. It is continuous, shaped every day by how you sleep, how you move, what you eat, and how you manage stress. Wearables fill that gap. They capture what happens between appointments. And when you bring that data into the conversation — when we can see that your resting heart rate has been creeping up over three months, or that your sleep efficiency dropped every time you had that after-dinner glass of wine — we can have a much richer and more productive conversation about your health.