Seasonal affective disorder (SAD), is a mood disorder subset in which people who have normal mental health throughout most of the year experience depressive symptoms in the winter or summer.
also known as winter depression, winter blues, summer depression, summertime sadness, or seasonal depression,
In the Diagnostic and Statistical Manual of Mental Disorders DSM-IV and DSM-5, its status was changed. It is no longer classified as a unique mood disorder but is now a specifier called with seasonal pattern for recurrent major depressive disorder that occurs at a specific time of the year and fully remits otherwise. Although experts were initially skeptical, this condition is now recognized as a common disorder. SAD's prevalence in the U.S. ranges from 1.4% in Florida to 9.9% in Alaska.
The U.S. National Library of Medicine notes that "some people experience a serious mood change when the seasons change. They may sleep too much, have little energy, and may also feel depressed. Though symptoms can be severe, they usually clear up."The condition in the summer can include heightened anxiety.