Thanks to Skillshare for supporting this episode, and this whole week, of SciShow. [♩INTRO].

If you follow any productivity gurus, then you’ve probably heard how you need to take cold showers in the morning. After all, not only can they wake you right up, but you’re also promised a myriad of health benefits and everybody loves a good healthy life hack.

But whether these claims are actually true is still kind of a gray area. Also, I have to say, as someone who grew up in Florida and now lives in Montana, a cold shower is different depending on where you live. So before you jump in that agonizingly cold shower, let’s look at some research.

One of the biggest problems with studying cold showers is that… well, people really haven’t. Instead, most health claims are implied from studies of cryotherapy using cold water or air to treat a condition or from things like people who repeatedly go swimming in cold water. But cryotherapy is really carefully controlled, and those swimmers often stay in the water for over an hour, so it’s hard to apply this to your quick rinse before work.

Still, that doesn’t mean there’s zero evidence for cold showers, because there is. It’s just not very strong. Like, take the claim people make that those showers improve your immune system.

In 2016, a study published in PLOS One wanted to see if taking a quick cold shower in the morning would reduce the amount of sick days someone took from work. For 30 straight days, more than 2300 subjects took either a warm shower, or a warm shower that turned cold for 30, 60, or 90 seconds at the end. On average, subjects in all three of the cold shower groups called into work 29% less than the warm shower group roughly the same as one less sick day per month.

But we don’t know why, since the research team didn’t measure any biological markers. Many of the participants did say they felt an increase in energy and continued taking the cold showers after the experiment, but that’s not enough to close the case. It’s possible that their white blood cell count increased like what’s been shown to happen with cold water swimmers.

But again, a 90-second rinse is a lot different from an hour in the water. Many people also swear that cold showers can boost mood. But the results there are maybe even weaker.

A 2008 study in Medical Hypothesis gets referenced a lot as evidence for cold showers as an antidepressant, but it’s not really all that convincing. They hypothesized that cold water would activate your sympathetic nervous system the system that does things like increase your heart rate and stimulate the release of endorphins which would elevate your mood. But it only had three data points, one of which was the author of the paper, and none of them had symptoms that would diagnose them with depression.

Plus, the biological markers they expected to change were never actually measured, so really we don’t have any results to go off of. To be fair, the author did mention all that in the paper. But alas, the blogosphere still holds onto that antidepressant claim even though the article wasn’t that powerful.

The thing here is, you can’t placebo a cold shower: you know if you’re getting one. So it seems like cold showers get a lot more credit than they deserve based on the evidence that exists. A short one probably won’t hurt you, but hey, let’s do more research before we start making claims about reality and our bodies.

Seriously, if you’re looking for a research project, this sounds like a good one to try out. Couldn’t be that expensive, it’s cold water. So, even though cold showers might not be the key to making you more productive, the CEO and co-founder of Skillshare, Michael Karnjanaprakorn, is really productive and shares his systems for productivity in his class Real Productivity: Create Your Ideal Week.

He provides a simple framework to prioritize and accomplish what’s important to you in the immediate and in the long term. We’ll make sure to link to it in the description. All these week, we’ve been sharing Skillshare classes we think SciShow viewers will appreciate, but even though the week is coming to an end, this offer from Skillshare is still available.

Skillshare is offering SciShow viewers 2 free months of unlimited access to their platform of over 20,000 classes. Click on the link in the description to sign up, and let us know in the comments what classes you take! We always love to learn new things. [♩OUTRO].