12 Health Mysteries Explained
Lots of hypotheses, not one perfect answer, says William Schaffner, M.D., chairman of the department of preventive medicine at the Vanderbilt University School of Medicine, in Nashville. A leading theory is that confinement breeds infection. In winter, Schaffner says, we spend more time indoors, in rooms that may not get a lot of circulation, giving us more opportunities to be exposed to respiratory viruses. The winter air, inside and outside, also tends to be less humid, drying nasal passages and making them more vulnerable to viral invasion. Still, Schaffner adds, the cold environment itself has not been proven to make people get sick in the winter.