How does a garmin running watch, like a Forerunner 955, infer sleep quality when the watch is not worn during the night but rather put on after getting up in the morning? You would think that it can't do that. at all, but, I regularly experience that, about an hour or so after putting it on in the morning, it'll vibrate with an alert for me, and when I look at it the screen is saying that poor sleep has delayed my recovery time, and indeed, I look at the recovery time, and it has just doubled. So, *somehow*, the watch thinks it knows how I slept.
