The Surprising Secret to Staying Cool in the Heat

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You know, I’ve heard time and time again that when it’s ridiculously hot out, it’s better to drink hot beverages than cold ones. “It’ll cool you down better,” the proponents of this strategy proclaimed. I’ve never been totally convinced that it would actually work, though, largely because no one had ever been able to explain why it works — the most anyone could ever say was something like, “Oh, well, it makes your body warmer on the inside, which makes the outside temperature feel cooler.” While this explanation isn’t entirely correct, it turns out the hot coffee/tea/whatever drinkers actually are onto something. Here’s the science behind the “drink hot stuff when it’s hot out” idea:

Melissa Dahl of NY Mag’s Science of Us ran into the same confusion I did recently and dug up some research conducted in 2012 to figure out what was going on. The paper, which co-authored by University of British Columbia Centre for Heart, Lung, and Vascular Health PhD candidate Anthony Bain, found that “body heat storage during physical activity is lower with hot fluid ingestion under conditions that permit full evaporation.” Very science-y and impressive-sounding, but I think I speak for many of us when I say:

Bain wrote in an email to Dahl:

“When we’re hot, we naturally cool our bodies primarily by sweating, or more specifically by having the sweat evaporate from our skin (that’s important!). Our bodies sense changes in tissue temperature by a network of thermosensors located in the skin and in more central parts of our body, which send input to our brain (specifically, the hypothalamus), which then initiates sweating.

“When we take in a hot drink, it appears that the thermosensors located in the stomach become overactive, and send strong signals to our hypothalamus that we are hot. In turn, the hypothalamus reacts by initiating an over-compensatory sweating response. So, when this sweat evaporates from our skin, the heat energy we lose due to evaporation exceeds the heat energy gained by drinking the hot drink. In other words, it is because our body overacted to the hot drink that we end up cooler in the end.”

Basically, hot drinks trigger our sweat response, which stores up heat energy in our bodies; then, when the sweat evaporates, we lose way more heat energy than we gained drinking the hot beverage in the first place. Voila! Cool-down city.

As Policy Mic notes, this little tidbit is perfectly timed for those of us living in the northern hemisphere; this summer is shaping up to be toastier than usual, with above-average heat and a heck of a lot of rain hitting most of the country. California has it especially bad — they’re in the middle of one of the hottest years on record. Yikes. Sorry, guys — maybe it’s time to break out the Keurig and have at it?