When to use the Breathe app

Normally Apple Watch will record HRV data points during the day and night when you are still and rested.  These are the best times to create an HRV reading.

If you want to force a reading then you can use the Breathe app on Apple Watch. 

 However, bear in mind that if you do this you should:

• Be fully recovered from any activity
• Be still and rested and follow the instructions on the screen

If you don't then it is likely that the HRV either will not be recorded at all or it will be inaccurate. For example, reading directly after aerobic exercise could mean your body is possibly flooded with endorphins which can impact HRV so you may see a short term increased reading.

If you use the Breathe app a lot and get very variable readings then you may want to increase Smoothing to reduce the impact of that.