Acclimatizing to the blasts of winter

Tuesday is the first official day of winter. Are you feeling a little colder than you remember feeling at the end of last winter? It may be because your expectations haven’t been reset to expect the cold outside, or you haven’t pulled out your bulkiest sweaters yet.

But there’s scientific research that shows that at least parts of our bodies really are warmer at the end of winter than the beginning. Here’s why:

Feeling cold serves the same function as feeling pain. When you walk outside on the first really cold day of the year, the nerve endings in your skin send a message to your brain :”Hey, it’s cold,” they say. “Beware. You don’t want me to freeze to death.”  But then you keep walking outside, day after day, and you’re fine. And your brain takes note.

Dr. Ausim Azizi, professor of neurology at Temple University School of Medicine, says after being exposed to cold for a while, your brain starts to think the temperatures are normal.

“After a while it realizes (the cold) is not a danger to the body, and then it kind of relaxes,” Azizi says. The parts of the brain that react to danger create a new baseline for what’s actually dangerous.

This is where Andrew Young comes in. He’s an environmental physiologist at the U.S. Army Research Institute of Environmental Medicine. He says when we get cold our brain tells our nervous system to shrink the blood vessels near our skin. That keeps blood from reaching the surface of our bodies and cooling off, and then traveling to our vital internal organs and cooling them off. It’s a survival mechanism. But when your brain relaxes after a couple of weeks of being exposed to cold, it establishes that new baseline for danger, Young says, and this reaction lessens.

“So that if you go into the cold with bare hands or bare face,” Young says, “that perception of cold on your face or hands is no longer sufficient stress to trigger the nervous response that constricts the blood vessels.”

That means that blood will start flowing to those exposed parts of the body again, and your hands, face, and whatever else is exposed to the elements feels warmer. Unfortunately, the consistent warmth of spring and summer create a new homeostasis  — and we will have to go through the process again next winter.