How Often Does Apple Watch Measure HRV?
Series 12 and Ultra 4 can measure HRV as often as every five minutes. See how earlier watches differ, what happens during sleep, and how to check your actual recording times.
Baevsky Stress Index Explained: Formula and Interpretation
Understand the BSI formula with a worked example, learn what high and low values mean, and compare the original index with stress percentages and the Kubios scale.
MxDMn Explained: What Your HRV Range Means
See how the longest and shortest heartbeat intervals determine MxDMn, why extreme values matter, and how to read the result alongside AMo50 and Stress Index.
AMo50 Explained: What High and Low Values Mean
Understand the percentage in your HRV report, see a worked example, and learn how AMo50 differs from pNN50 and contributes to Baevsky Stress Index.
Can Apple Watch Measure Cortisol?
What HRV and stress scores can tell you, how cortisol is tested, and how to follow your readings with Wellhero.
