When the temperature drops, the chance of you coming down with a cold or the flu increases significantly. It’s widely accepted you’ll get sick more often in the winter. That’s because you’re likely to be inside more and the common cold thrives better in dry air than where there’s humidity, and, when you spend more time indoors, you’re exposed to more germs.

Here’s something interesting about the common cold: when your core internal temperature falls after exposure to cold, the immune system’s ability to battle the rhinovirus (the virus that causes it) is also reduced. The immune system literally slows down. Cold feet may also play a part. In a recent study, researchers made students sit with their feet in cold water for 20 minutes. These students were found to be statistically much more likely to catch a cold in the next five days than the control group (those who didn’t have to sit with their feet in cold water).

The flu virus is also transmitted much faster when it’s cold out becau...