[jph]

https://hbr.org/2018/03/cold-showers-lead-to-fewer-sick-days

The link is an interview with the study author, and excerpts are below.

This is the first high-level evidence showing that cold showers can benefit your health. People who took them for at least 30 seconds for one month called in sick 29% less than our control group — and 54% less if they also engaged in regular physical exercise.

Participants who took the cold showers actually reported feeling ill just as many days, on average, as the people who showered normally. But either their symptoms were less severe or they felt more energetic, so they were better able to push through the sickness and function anyway. The exact effect on the immune system is unclear, but we do have some knowledge of the pathway through which it works. Cold temperatures make you shiver — an autonomous response to keep your body temperature up. It involves a neuroendocrine effect and triggers our fight-or-flight response, causing hormones like cortisol to increase, shortly before we shift to a relaxation response. Moreover, cold temperatures activate the brown — or good — fat in the body.

Brown fat doesn’t have any proven connection to immunity, but it does affect the body’s thermoregulation. When activated, it keeps the body warm by burning calories. It may also increase your energy and metabolism and help control your blood sugar. That could reduce your risk of obesity and diabetes.

[blowski]

Sounds spurious to me. I imagine people that take regular cold showers are also more likely to push themselves at work. To make this really interesting, you'd need to have a blind control group of people who are paid to have cold showers, and see whether their absence rates go down when they start.

[acqq]

My bigger problem is too short time span of the experiment:

“The intervention period was 30 consecutive days from January 1st-30th 2015. During the following 60 days January 31st-March 31st 2015 participants of all three intervention groups were instructed to shower as preferred.”

[blowski]

Indeed. The whole article has a strong whiff of confirmation bias to it.

[OJFord]

And the time of year - I think absence (for any reason) is lower in January anyway as a lot of people have just come back from a week or two off.

[akuji1993]

We also don't know, but can highly suspect that the subjects in the cold shower group knew or could guess, what was wanted from them in this study. See, Prison Experiment by Zimbardo for the most extreme example, but people will behave in the way they "should" when you tell them the reason of your study.

The fact that the illness days didn't decline makes this study less viable. I'd like to see a followup, but it's hard to imagine a solid base to keep the participants in the dark. It should also be much longer than 30 days.

[kiliantics]

You couldn't have a true "blind" control group, as there is no way a person could not tell that they are being showered by cold water as opposed to warm water.

[marblar]

Well, you could sedate both groups before the shower and dry them before waking.

[mrmuagi]

I agree to the spurious claim. To shower in the cold is willingly doing something unpleasant. That in itself feels like it is going to affect their attitude towards coming into work -- when doing so is unpleasant.

[Clomez]

This seems almost more dangerous, so people who took cold showers feel just good engouth to become vector for more infections? that's pretty crazy and i would argue the overall effect is then very very negative.

[lbj]

That doesn't sound healthy at all. If the only difference is that they went to work sick, then I see little benefit. Except to the disease of course, it get spread around more effectively.

[joncrane]

The takeaway I get is that it increases perseverance. So basically, "doing something physically unpleasant every day increases ability to push through/withstand other physically unpleasant events" is my big takeaway. Seems pretty straightforward. Not necessarily novel, especially when you add in the exercise portion.

I think there's some value to pushing yourself harder than the minimum to be comfortable and survive. But I don't think that's a eureka.

[viceroyalbean]

There are some parallels to Stoic philosophy there. Ancient stoics would exercise regularly but state the health effect as a secondary benefit, the primary benefit being the virtuous exercise of discipline.

[gambiting]

Anyone who had to do military draft will confirm it. Even after 9-12 months of mandatory service you don't come back buffed like a body builder - but the daily exercise and regime puts you in a different state of mind.

[imglorp]

Navy SEAL training involves extended cold water exercise specifically designed to build perseverance. The ones that succeed are experts at not quitting anything

[gwd]

> The takeaway I get is that it increases perseverance. So basically, "doing something physically unpleasant every day increases ability to push through/withstand other physically unpleasant events" is my big takeaway.

Yeah, that's the hypothesis I need to see falsified before I start taking cold showers. I reckon my 'perserverance' muscles get enough of a workout from fasting.

[watwut]

So basically, "doing something physically unpleasant every day increases ability to push through/withstand other physically unpleasant events" is my big takeaway.

Meh, that would require an independent confirmation too. It is harder for me to believe that doing one somewhat uncomfortable thing a day will make you more likely to push through multiple other more uncomfortable things.

[chongli]

Does it increase perseverance or merely select for it? This study does not distinguish the two and to me the latter is more likely.

[iandanforth]

That's what the randomization protocol is for?

[caleb-allen]

I wonder if mouthwash is similar, if to a lesser degree? Every morning I use mouthwash until I've "felt" all the pain of it, which is when I am done. And I always hate it, and it never gets easier, but I always feel better afterwards because I accepted the pain.

[SuoDuanDao]

I'd imagine the symptoms were also reduced. Cold showers reduce inflammation, so I'd imagine people who practice them would feel less miserable once the 'fight it off' portion of the infection is over.

[dkersten]

My doctor also recommended cold showers (or at least ending with a minute of cold) as a means of stress management. Apparently it stimulates some nerves and reduces the stress damage somewhat. Possibly related to lower inflammation too. Anecdotally I do feel better when I do it and miss it when I don’t.

[lucideer]

The problem you're describing sounds more like a societal/work-culture problem that's completely orthogonal to the study.

Cold showering improved individual health: the fact that those experiencing said improved health made unwise decisions that may increase the spread of disease doesn't change the fact.

[feintruled]

Perhaps what we have here is a concrete example of the principle put forward by Mark Twain - “Eat a live frog first thing in the morning and nothing worse will happen to you the rest of the day.”

[quattrofan]

Lots of science to back this up, look up Wim Hof

[lbj]

He's an impressive beast.

[edf13]

> Brown fat doesn’t have any proven connection to immunity, but it does affect the body’s thermoregulation. When activated, it keeps the body warm by burning calories. It may also increase your energy and metabolism and help control your blood sugar. That could reduce your risk of obesity and diabetes

Wonder what effect this would have on a weight loss program?

[ericmcer]

It makes sense to me that our body would behave as conservatively as possible with nutrient stores in normal conditions. Plunging them into a crisis state, like a cold shower, would then trigger some kind of “use it all we are in trouble” type response.

[ripsawridge]

I'm interested, and will probably try it. But! I'll keep the # of sick days the same. They are wellness days, when I take care of other business.

[everdrive]

What does it mean to “activate fat?”