Blankets were invented to sleep comfortably in a unheated room. But now, in our modern society, most everyone sleeps in a warm room. So why do we still use blankets? I asked 12 friends in my dorm, “Do you have trouble falling asleep if you don’t have a blanket or sheet over you?” The results were not surprising; only one out of the 12 people said they felt totally comfortable falling asleep without a blanket. Why is this? We don’t need blankets to survive, yet most of us can relate to that blissful feeling of slipping under a thick comforter and drifting off to sleep.
Evolutionarily, anything we do that makes us feel good must have some sort of survival benefit. This explanation easily applies to why using a blanket to sleep makes us feel good; if you were to bring your mattress outside on a cold winter night and sleep on it, a blanket would be highly advantageous to your survival. But even though it feels good to cuddle up under a warm blanket inside your warm bedroom, do you actually need it, and is it good for you?
Humans did not evolve to constantly exist within a window of comfortable temperatures. Rarely are we cold for longer than the time it takes to walk to class. Evolution has taught humans to always seek comfort because it was never the norm, but now it is. How does that affect our bodies? Not well. Indoor heating has bred a society of cardiovascular weaklings. According to the American College of Cardiology, cardiovascular disease is the leading cause of death for both men and women, accounting for one in every four deaths in the United States. If you’re cold, your heart has to work hard to keep you warm. Being cold is a cardio workout, and indoor heating is depriving our hearts of the hard work they would have to do almost constantly during the winter, therefore atrophying them.
Another major health problem in the United States is obesity. According to the National Institute of Diabetes and Digestive and Kidney Diseases, 70.2 percent of all Americans are either overweight or obese. Being overweight means one has an unhealthy excess of white fat. There are two different types of fat, brown and white. White fat stores calories and is considered to be unhealthy, whereas brown fat is metabolically active. Having more brown fat correlates to being younger, skinnier, and healthier.
When we’re cold, our bodies warm themselves two ways: shivering and burning brown fat. Chilly weather triggers our bodies to produce more brown fat to burn. Thus, cold exposure may promote a healthier body, one of more brown fat and less white fat.
Aside from strengthening one’s circulatory system and causing the body to have more healthy brown fat, cold exposure has also been shown to reverse the symptoms of diabetes, another widespread disease caused by our modern society. A study by Wouter van Marken Lichtenbelt in 2015 took eight men with type 2 diabetes and kept them in a chilly 14-degree Celsius room (the temperature just above the point where people start shivering) for six hours a day for 10 days. At the end of the 10 days, researchers measured their blood insulin levels and found that the men’s bodies metabolized sugar 43 percent more effectively than when they began, indicating cold exposure may reverse the symptoms of diabetes.
I’m not saying our species’ recent lack of being cold is causing heart disease, obesity, and diabetes, but it could be a contributing factor. I personally have been taking a cold shower every day for about a year. Though initially difficult, after a couple months it became easy, and I now look forward to it every morning. Not only does it wake me up, but my cold tolerance has improved, and I shiver less often. Give it a try yourself—there is some benefit to the outdoor saying, “Be bold, start cold.”