Does Your Smartwatch Actually Know Your Health? (The Real Truth)
Let’s be real . You wake up, check your smartwatch, and it tells you exactly how well you slept, a precise percentage, a "sleep score," maybe even a breakdown of deep sleep versus light sleep. You believe it completely. It's on your wrist. It has sensors. It must be accurate, right? Here's a question worth actually sitting with. How much of what your wearable tells you is genuine medical-grade measurement, and how much is an educated guess, dressed up in a clean, confident-looking number? The honest answer might surprise you, and understanding it actually makes these devices more useful, not less. What Wearables Are Actually Measuring Most fitness trackers and smartwatches use a method called photoplethysmography, sensors shining light into your skin and measuring how it reflects back, to estimate your heart rate. From that single measurement and a few others like movement patterns and sometimes blood oxygen estimates, your device builds everything else: sleep s...