Here’s how Garmin keeps tabs on my drinking

Your heart is working double shifts the next day after a party. And your Garmin knows it.

I occasionally enjoy a beer or two just as much as I enjoy a good trail run. But if I run the morning after some outing, I wonder, does my running coach know why I am slower that day? The majority of my running sessions are heart rate-based runs — run slow to run fast.

This means that I have, for example, to run 10 kilometres without my heart rate climbing over 140 beats per minute. Having helped the body to process even a moderate amount of alcohol, the heart is more tired than usual, and so I have to go slower just to keep it safe and satisfied.

It’s astonishing how well Garmin (and maybe other smartwatches) register those social outings. Just by checking my heart rate balance and sleep score calendar, you could tell when I was out in town!

For example, my friend and I shared a bottle of wine (might be just a rough approximation of what we actually shared) on Tuesday. At night, the average HRV (heart rate variability) dipped way below 40 ms, and it stands out. Sleep score fell to 47 (out of 100), signaling I didn’t have a very good rest, even though I got seven hours of sleep.

According to the literature, HRV should fall between 40 and 60 milliseconds. Consuming alcohol leads to decreased HRV, increased resting heart rate, and delayed recovery.

Not rocket science, but having a watch constantly reminding you of the price of your decisions makes you question your choices.

This is not a groundbreaking discovery, I’m well aware of that. People similarly into health data as I am have long noticed the impact substances have on one’s recovery. Has it influenced users’ decisions? Who knows. Many claim it did.

“It's like Unalive Juice,” one user shared in a thread on Reddit.

Others claim the Garmin smartwatch has simply made them feel guilty about drinking, or shared some useful advice on how to make it a little bit better.

“My hrv drops like a stone too after a few pints but if I 'cheat' and have some food on the night and some water it's not as bad the next day,” one user said.

The Reddit user who started the thread shared a sleep score of 64 (out of 10). But some claimed they have a worse result even on a regular day, no alcohol involved.

“I mean… this is a normal sleep for me. I wish I slept as “bad” as you lol,” one user said.