A Firm Resolve

Lack of sunshine causes Seasonal Affective Disorder for many

In a Weather.com poll, 69% of people said they are in a better mood when the sun is shining, compared to 24% who said the sun doesn't affect their mood and 7% were unsure.  Of course, these results are not scientific and those drawn toward Weather.com are not necessarily a typical audience.  In any case, seasonal affective disorder (SAD) is real and is also known as the "winter blues".  It's when people experience depressive symptoms due to lack of sunshine.  SAD is almost nonexistent in the tropics.

Men think jokes are funny by default, women subject jokes to more scrutiny

In a report published in the Proceedings of the National Academy of Sciences by Dr. Allan L. Reiss from the Stanford University School of Medicine (see "Who is more likely to enjoy a good joke?"), men automatically expect jokes to be funny while women subject jokes to greater scrutiny to see if they are funny.  Thus, women have higher cognitive expectations of themselves in dealing with humor.  Dr. Reiss thinks there could be some connection with the higher rates of depression among women.

Even broader, the findings agree with common knowledge that women have higher expectations of themselves in social situations than men.  The pressure to meet their high self-expectations can gradually contribution to emotional tiredness and a slow and gradual collapse into depression, if not caught sooner.