> who logged sauna sessions via connected apps

It seems you ask participants to log if they went to sauna. Out of curiosity, why is it not simple to also ask for a type?

i was mostly refering to humidity/duration/temperature given that most devices do not report back these values

I'm equally confused as the other person above. Why not just ask participants to report what type of sauna they used? Sure humidity/duration/temp would be awesome to have, but at the very minimum knowing if a dry sauna would get the same results as a traditional steam sauna.

What if they jumped between saunas? And with self-reporting, the more you ask I guess the less precise the result... Sensors, however...

There's quite a wide range of variation between "full dry" (no added humidity whatsoever) and "full steam" (an actual steam room, rather than a sauna). Just asking people was it dry or was it humid won't capture much of that variation. I have a steam room at home and have been a near-life-long lover of them - they are wildly different than a sauna. But I'd still rank a sauna where someone had dumped 1L or so of water over the heater to be "humid", and consider it also very different from a totally dry sauna.