[wensheng]

It says old showering reduced self-reported sick leaves but not illness days. So it's not conclusive it has real benefits.

I guess lots of HNers shower cold, they like hearing it having potential benefit so they can feel good about themselves. Lots of confirmation bias here. The top voted comment doesn't discuss TFA, but just how great cold showering is.

In the study, a 90-seconds subject died, most likely not because of cold shower, but you never know, without the the experiment, he/she probably would have lived. His/her family members probably blamed cold-shower for it.

Dr. David Sinclair advocates cold-showering, said it increase brown fat. But the evidence he cited[1] (Lifespan page 110), the short term cold exposure is 4 hours, the temperature is probably lot colder than cold shower, so it's doubtful a 30/90 second cold shower help growing brown fat.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5558157/

[QuarterReptile]

Just feels like sampling bias. As someone who likes to take cold showers (typically with 60-64F water), the thing that usually stops me is feeling sick.

I think it's likely that a significant portion of attrition (19% after 90 days) was due to people feeling too sick to suffer a cold shower, which should pretty closely track with people feeling too sick to go to work.