Are cold showers good for your health? Let’s look at the research.
The most frequently cited study – basically the only RCT study – to suggest real-life health benefits of cold exposure is from the Netherlands by Buijze et al. This study investigated the effect of ending your showers with 30, 60 or 90 seconds (3 groups + control group) of the coldest shower temperature (minimum 10°C based on Dutch ground temperature at the time). They were told to do this for at least 30 days and recommended to do it for 90 days, which most did. During this 90-day period, the researchers monitored the subjects’ health.
The finding that made headlines everywhere was that the cold shower groups called in sick for work 29% less than the control group. What usually didn’t make the headlines was that there was no significant difference in illness days, suggesting that they weren’t actually sick less but just went to work anyway. Maybe after their cold showers they felt like Wim ‘The Iceman’ Hof and marched to work feeling invincible, humming “Can’t be touched” by Ron Jones Jr. while occasionally coughing and sneezing.
The effect on work absenteeism also wasn’t consistent in the first place. Median sickness absence days didn’t significantly differ between groups for the first 30 days. And while 29% less sickness absence over the 90-day period sounds great, the actual percentage of people that had a sick leave was almost the same for the control group as the 60s and 90s cold shower groups: 35% vs. 34% and 33%. Only the 30-second group differed more considerably with 29%. There was thus clearly no dose-response effect of the cold showering: longer wasn’t better.
The groups also didn’t significantly differ over the 90-day period in work productivity, which would technically mean they weren’t productive at all on those extra days they showed up for work. There was also no difference in anxiety scores. They did self-report higher quality of life after the first 30 days, “although this [effect] was deemed too small to be clinically relevant” and stopped being significant altogether after 90 days for both the mental and physical components of quality of life.
The study also suffered from relying purely on online self-reported measures, as well as sampling bias (scaring off anyone unwilling to take cold showers) and survivorship bias (20% dropped out, likely the weakest individuals).
Overall, this famous study only provides very faint evidence for health benefits of cold showers. The small, inconsistent benefits that were observed could have easily been placebo. If you read my book, you know I still think cold showers can be beneficial for their acute mental energy boost, similar to a shot of adrenaline, but I wouldn’t expect any magic from them for your health or fitness.
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