The impact of coffee and energy drinks

Many, but not all, people experience a sympathetic response (alertness), i.e. reduced heart rate variability (HRV), when they drink coffee.

There is a large study showing that HRV is lower in coffee drinkers but that this effect is more likely to be due to the fact that these individuals statistically drink more alcohol and smoke more often, both of which clearly lower HRV. However, the study found that high long-term coffee intake (4+ cups per day) tends to lower HRV. As for energy drinks, research is scarce but the effects should be similar to those for coffee.

Feel free to test for yourself using the graphs in the app to see how you are affected by coffee and/or energy drink intake if it is something you usually consume.