The Sun Factory Online
According to the American Psychiatric Association, up to 20% of Americans may experience symptoms of depression during the fall and winter months. Those who work long hours in office buildings may experience these symptoms year round.
SAD is linked to a chemical imbalance caused by a shorter days and lack of sunlight during the fall/winter. Younger adults and women seem to be the most at risk, especially during January and February.
So what can you do? The APA suggests increased exposure to sunlight.
The Vitamin D doc says in his blog that he believes SAD "is primarily a disorder of sunlight/Vitamin D deficiency." As he states, "Everyone that has ever ventured outside on a sunny spring day after a long winter, or even visited a tanning bed during winter, know how much the mood is elevated by the experience. It is likely that the combination of light and Vitamin D produce the effect. Keep your Vitamin D levels high this winter!"
More information can also be found in this CNN article.