What is your heart rate variability and how much does it vary? What do you do that increases it?
I have noticed that when my overnight hrv is low I feel terrible the next day so I have been trying to work out the reason for the variation. It does seem to be linked to how much sun I had the previous day so I am wondering if vit d would help boost it.
Low hrv for me is around 16. It seems to go up to 30 something after a sunny day in the UK and 40 on holiday somewhere hot.