HRV and Stress: What Heart Rate Variability Can and Can’t Tell You
HRV responds to stress, alcohol, breathing and exercise. Here is what the research shows it can tell you, and why it is not a score for how well you will think.

HRV responds to stress, alcohol, breathing and exercise. Here is what the research shows it can tell you, and why it is not a score for how well you will think.

“Biohacking” gets treated as one philosophy, but sauna, cold exposure, HRV tracking, and fasting each have wildly different evidence behind them. Here’s what each one actually shows — including an honest null result for HRV and cognition that rarely gets mentioned.