Since I’ve been in an open-secret sharing mood lately, I have another confession to make; I love taking cold showers. I love how they feel on my skin, I love how low the humidity is afterwards, I love the feeling of hunger a few minutes after drying off, and I love the cold feeling of my extremities afterwards. I also love embracing a mildly difficult obstacle early in the day; I feel I become a slightly more resilient man after embracing the low temperature rinse. So yes, while I’m not as obnoxious as the intermittent fasting cult, I guess this does make me as bad as the hustle bros. The International Electronic Echo Chamber aka the internet has no shortage of articles and videos proclaiming the numerous benefits of taking cold showers. However, being that I am a man of science, I wanted to take a look at the evidence for myself.
Much like I did with my NSFW Fermi problem, I’m going to lay down some ground rules with my thought process. This is necessary because some guardrails need to be established for what constitutes good science. I used Google Scholar as my search engine for looking up scientific studies. Google Scholar only contains scientific studies, and will not lead users to some idiot’s blog or to some site that wants to sell you something; fact-finding missions require a proper fact-finding radar. I only focused on links from the first two pages of the results because Google sorts by relevancy. “But Dan, I found a study buried on page 19, that tangentially says something semi-important regarding” dude, just stop. If it was so pertinent to what I searched for, then it would have appeared far sooner. Don’t like it? Then go sharpen a pitchfork.
As far as search results go, I also didn’t consider studies cowering behind a paywall. I wanted to be as fair as possible, hence I only wanted to consider studies that anybody else with an internet connection and too much time on their hands would have access to. That, and I’m just too cheap to pay for the studies. I also restricted my searches to papers from 2019 onwards. The internet has blown up about the virtues of cold showers in the last few years, and this served as a fair line in the sand-albeit an arbitrary one. Also, this will allow for a potential body of evidence to develop, as opposed to only accepting studies from the last six months.
Furthermore, I didn’t count case studies in my search. Case studies are not a controlled scientific experiment. In the words of a Navy-veteran TA I had in college, they’re more of a look at me, here’s my story. I want empirical evidence and not anecdotes. I also didn’t consider meta-reviews either. This is mainly because these types of literature reviews give a quick summary while often times skimping on important details such as the methodology used or the number of participants in the study. I needed to see the thought process of those conducting the study, and a meta-analysis is not very conductive for that.
Next, I only examined considered studies that explicitly mentioned cold showers in their methods section. Most people take showers at the start of their day, and are not immersing themselves in an ice bath for extended periods of time, nor are they swimming in arctic lakes like Wim Hof. Nobody has a cryo chamber in their home either, except for future CTE case-study Antonio Brown. Point being is that I wanted studies whose methods actually aligned with how the practice would be performed in the real world.
Then, I only considered studies with a minimum of 100 participants. As we all should’ve learned in science class, sample size matters. One cannot make population-scale judgments based off of tiny population sizes; the risk for sampling bias is just too great. Large populations of study participants tend to have people of varying ages, genders, genetic makeups and so on, thus making it easier to make population-level claims. This happens all the time in fields such as nutritional studies and clinical drug trials, so this isn’t an unrealistically high expectation to set.
Speaking of, I only considered human studies. I know this will be a hot take (though definitely not my spiciest one) but I frankly don’t care about the results from animal studies. At least, I don’t care about them enough to directly map their results onto my life or the lives of millions of humans. Promising results in animal studies can definitely be used to jockey for more funding to run human trials, so they are definitely useful. However, since studies regarding humans taking cold showers are neither expensive nor unethical, there is no reason for me to care about what happened in the horse stable or inside the mouse cage.
“Geez Dan, are you done ruling out studies? I’d swear you were just out for conformation bias or something” an annoyed reader will protest. Yes, those are my guardrails and no, I won’t apologize for setting some achievable standards as to what I’ll consider robust enough for mainstream lifestyle advice. Given that start with cold showers is often peddled by non-scientific social media influencers such as a film-school dropout turned YouTuber, it’s fair to say that he’s presenting this to a large, general audience. As for my personal biases, I wanted to find evidence to support my morning habit, not to debunk it. Why would I want to come up empty-handed and look like a fool?
Aaaand, here’s the part where I look like an utter fool. I examined a lot of the health claims made by self-proclaimed lifestyle gurus (eww…pundits) and videos on YouTube. I typed “cold showers” and “[insert topic here]” into Google Scholar. I searched for testosterone, skin, hair, metabolism, sleep, arousal, muscle recovery, stress, mood, circulation, and immune response. While many studies came up, literally none of them met my fairly lax standard of acceptance. The most common reason that I found was that the sample size was far too small; we will not make population -level claims when the study size is 40 or less. There were a few animal studies that came up, but I frankly didn’t even bother to read those. I had to rule out immersion studies as well. But yes, not a single robust-enough study upheld any of these pop-culture claims.
Now, that doesn’t mean that there isn’t something to the studies that I ruled out. If promising results were found in the small population studies, then that could absolutely be used to justify performing a similar study on an appropriate-sized sample. This isn’t just a naïve writer spouting nonsense either, this is how the FDA expects drug companies to test their products prior to approval, Phase 1 is small, and Phase 3 is large. Therefore, we should consider cold showers the same way we treat early-stage medicines; approved for the next round of trials! As a man who just outed himself as a biased fool, believe me, I want future scientific studies on this topic to avenge my low-temperature opinion.
At the risk of sounding like a less-impressive Neil deGrasse Tyson, the lack of scientific literacy amongst the population is what allowed the belief of cold showers being a panacea to become so widely believed. If the average person had even a mildly stronger grasp of the importance of sample size or methodology, then this article wouldn’t have been needed. I say this not to throw shade at my fellow citizens; our education system doesn’t go into these topics until college. K-12 science classes treat science as a learn-and-regurgitate subject rather than as the method for discovery that it is.
Plenty of blame can be thrown at the media as well. The news tends to strip away the details of a study in favor of reporting a catchy-sounding headline such as New Study Says Drinking Wine Prevents Aging! Time-pressed Americans won’t have the extra bandwidth to scour the study in question and examine the methodology used. Whether this is by a conspiratorial design to keep viewers ignorant or whether it is just because the news has only a few morsels of time to dedicate to the story before switching gears to the radicalization Flavor of the Week, the result is the same: a misled audience.
“Well Dan, now that cold showers haven’t met your scientific muster, are you going to stop taking them and go back to being a normie?” a weirdly curious reader might ask. Honestly, no. I base that on the completely nonsensical part of my brain that says it feels good and I like it. The fact that there is at least some lower-level evidence to support this activity and that I fit into the sample demographic of the smaller studies (male, young, no chronic health issues), means that cold showers aren’t a ridiculous or harmful idea, we just need a larger mound of evidence before we make population-level claims.
“Extraordinary claims require extraordinary evidence”- Carl Sagan.
Home Page 