This is a highly contested question among scientists and physicians. One one hand, its hard to deny that at least anecdotally, we see more sick people during the winter. But what does the science say? Here are summed up perspectives on the debate.
NO: Cold weather doesn’t cause colds. Carl Olden, MD notes that at least from an epidemiology standpoint, people who live up north in Alaska and Canada do not have higher incidence of sickness than people who live in Australia.
“These are old wives’ tales from an era when we had no ability to treat fever or other complications of infection. Folks created myths to explain what happens to protect their children from getting sick.”
YES: Hypothermia suppresses the immune system. A publication from Critical Care in England notes:
In vitro studies and clinical observations suggest that both accidental and controlled/therapeutic hypothermia have a strong immunosuppressive effect, and that hypothermia increases the risk of infections, especially wound infections and pneumonia.
NO: Acute cold exposure activates the immune system. A study out of the Army Research Institute of Environmental Medicine suggest acute cold exposure can stimulate the immune system. Dr. Belilovsky attributes the response to hormones such as norepinephrine, the flight-or-flight catecholimine.
Researchers examined the immunological responses to cold exposure and found that acute cold exposure, such as going outside without a jacket, actually appears to activate the immune system.
YES: Cold weather causes vasoconstriction to retain heat. Vasoconstriction narrows blood vessels, leading to dryness. Some physicians note that dry mucous linings in the nose may make one prone to respiratory infection.
NO: Lastly, many people note that during time of colder weather, people tend to spend more time together in enclosed areas. Increased exposure to other people increases occurrence of sickness, not the cold weather.
What interpretations you choose to draw depend on your take of said points, but there is substantial reason to believe both sides of the debate. Personally, I’d rather not take the chance and brace myself for sickness during cold weather.