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Your smart ring does not measure sleep stages. It measures heart rate and motion, then guesses. Here's how the guess works, why the industry pretends otherwise, and why Pulsyn tells you the truth.
Your smart ring does not count your breaths. It counts the ripples that breathing leaves on your heart rate, then runs statistics to guess how many times you inhaled. The method is real. The precision is not.
Most wearables report resting heart rate as the lowest heart rate they can find, usually during sleep. The clinical definition is different. Pulsyn measures it during motionless awake periods, and the gap between the two definitions is often 10 to 15 beats per minute.
Smart rings promise workout tracking, but the physics of finger blood flow makes PPG nearly useless during exercise. Here is why the heart rate data is often fabricated, and why Pulsyn does not pretend otherwise.
Most smart rings shine light into your finger and count the bounces. The ones that do it well sample at 100 Hz or higher, use green and infrared LEDs in a specific geometry, and process the signal before it ever reaches a server.
Your smart ring is guessing for the first two weeks. Every sleep score and recovery metric is built on population averages until the algorithm learns what normal looks like for you. Most companies do not tell you this clearly. Pulsyn does.
The wrist is the worst place to measure heart rate during sleep. It is too thick for transmissive PPG, too prone to motion artifact, and too thermally unstable. The finger wins on every metric that matters for overnight biometrics.
Consumer wearables run reflective PPG on body parts never designed for it. The FDA has scrutinized these monitors since 2022 for systematic bias. Smart rings compound the problem with clamp pressure and unvalidated algorithms.
