Smartwatch health tracking accuracy: how reliable are the sensors and metrics?

22 Eki 09:45

I've been reading about the various health metrics smartwatches claim to monitor—heart rate variability, blood oxygen, stress levels, even sleep stages. How accurate are these measurements in everyday use, and what factors can affect their reliability? Are there best practices to ensure consistent data, or should we treat them as rough estimates? Would love to hear experiences and thoughts from the community.