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.
Apple Watch
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.
