Despite being brutally long, there may be another reason to dislike Chicago winters. And we're not just talking about those of you who suffer from seasonal affective disorder.
"Our northern locale and dreary winters means less sunlight hits our skin, resulting in a lack of the immune system-boosting vitamin D. And some experts say the key to warding off illnesses like swine flu, is a strong immune system," writes Alex Parker on ChiTownDailyNews.org.
Indeed, the Mayo Clinic lists protection from autoimmune diseases among the benefits that vitamin D provides.
Low vitamin D levels during the winter, when there is less sunlight, had a direct connection to rising flu cases, Boston University professor of medicine, physiology and biophysics Michael Holick concluded in the medical journal Epidemiology and Infection.
In the winter, it's impossible to produce vitamin D from the sun in areas north of Atlanta because the sun never gets high enough in the sky for its ultraviolet B rays to penetrate the atmosphere, explained an artilce from U.S. News & World Report last June.
When the sun's UV-B rays hit the skin, a reaction takes place that enables skin cells to manufacture vitamin D. If you're fair skinned, experts say going outside for 10 minutes in the midday sun -- in shorts and a tank top with no sunscreen -- will give you enough radiation to produce about 10,000 international units of the vitamin. Dark-skinned individuals and the elderly also produce less vitamin D, and many folks don't get enough of the nutrient from dietary sources like fatty fish and fortified milk.
But while vitamin D is helpful, it shouldn't be considered a panacea.
"Vitamin D is not a miracle drug," Horlick said. "But if you sustain healthy levels, it's likely to provide you with many health benefits, and reducing the risk of infectious disease."