The fact that it is cold will not, in itself, cause you to become sick. The reason why colds become more prevalent in winter is that people tend to stay indoors more, where they come into contact more frequently with other people, some of whom may be carrying viruses or illness-causing bacteria. Also, indoor heating systems run constantly—in colder regions, anyway—and the environment inside homes and buildings may not be all that healthy. Germs can proliferate in, for example, air filters and air ducts that have not been properly cleaned. Sometimes, too, people can be exposed to too much carbon monoxide, and the early symptoms of carbon monoxide poisoning can mimic those of a common cold.

To help avoid winter colds, it is wise to wash your hands regularly and, when in public areas, try and keep your hands away from your mouth, nose, and eyes. Recent studies have also shown that a good night’s sleep (eight hours) helps to reduce the chances of getting a cold by 66 percent.