http://articles.mercola.com/sites/articles/archive/2005/04/20/seasonal-affective-disorder-part-one.aspxSeasonal affective disorder (SAD), a syndrome characterized by recurrent depressions that occur annually at the same time each year, affects an estimated 4 percent to 6 percent of the general population. It's the prevalence of SAD and other depressiveenCommunityServer 2008.5 SP1 (Build: 31106.3070)