What is the definition or description of: seasonal affective disorder?

SAD definition: Wikipedia states:in the diagnostic and statistical manual of mental disorderss dsm-iv and dsm-5, its status was changed. It is no longer classified as a unique mood disorder, but is a specifier for recurrent major depressive disorder called with seasonal pattern that occurs at a specific time of the year and fully remits otherwise.

Seasonal Affective : Disorder (sad) is seasonal depression thought to be related to seasonal decreases in sunlight exposure. One effective treatment for sad is light therapy. There are many products on the market. One that i think is well researched is phillips golite available through costco, amazon, and others. A psychologist or counselor who treats depression may help with any other contributing factors.