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Heat and humidity zap our energy levels during the day, but when it's time to hit the hay, a slightly elevated body temperature — paradoxically — may keep you awake.
Turns out there's a quick and easy way to sidestep this issue, as New York Magazine wrote back in 2014, which doesn't involve expensive supplements or time-consuming smart phone apps.
Their trick? Poke one or two feet out from under the covers to ease your way into snooze town.
I can attest that this actually works — but why?
The truth is that scientists don't really know. Researchers haven't designed any studies looking at why or how an exposed foot can help someone sleep better; but they can muster a guess.
Natalie Dautovitch, a spokesperson for the National Sleep Foundation and a psychology professor at the University of Alabama, told New York Magazine that it's likely tied to regulating body temperature.
Right before you fall asleep, your body begins to power down by shuttling heat away from your body. In fact, your sleeping temperature is about one to two degrees Fahrenheit cooler than when you were awake. Scientists think this allows us to conserve energy during slumber so that you can wake up energized and refreshed. Keeping our bodies warm takes energy, after all.
There are two reasons why feet are a good way to cool down the body. First, your feet are relatively hairless appendages, Dautovitch told New York Magazine, which makes them better at conducting heat away from the body.
Second, they contain special types of blood vessels called arteriovenous anastomoses that shunt heat away from the body. These types of blood vessels are most prominent in the pads and nail beds of our fingers and in our toes, but are also spread across our ears, noses, eyelids, lips, cheeks, and forehead. That's why your fingers, toes, and nose get coldest when it's chilly out.
We've known for a while that in addition to the inability to regulate body temperature, various other factors including our genes, exposures to certain lights from laptops and smartphone screens, and exercising or eating close to bed time can worsen sleep. But as a whole, scientists still aren't quite sure why the estimated 5 to 15% of people suffer from insomnia.
Either way, next time counting sheep or dousing your eye mask with lavender essential oils isn't working, try sticking a foot outside the covers.
For more on the science of using your feet to sleep, check out this video by New York Magazine's Science of Us: