How to read HRV, sleep and resting heart rate honestly — including why a trend that moves with your protocol is not proof that it caused it.
Start hereWhat HRV, resting heart rate and sleep stages actually measure, how much they move in healthy people who changed nothing, and how to tell a real trend from ordinary noise in your own record.
Apple Health and Health Connect share data per type and per direction, store it on your device, and let you revoke any single type — here is exactly how each one works and where the controls are.
Heart-rate variability arrives as a single tidy number that looks like a score — but the healthy adult range is so wide, and the measurement so sensitive to conditions, that only your own rolling trend carries information.