Sad (Seasonal Affective disorder)

WHAT IS SAD???

Seasonal affective disorder, or SAD, is a kind of depression that appears at certain times of the year. It usually begins in the fall when the days get shorter and lasts through the winter. SAD doesn’t only happen in the colder months though. A less common form of seasonal affective disorder affects people in the summer months and usually starts in the spring. It isn’t really clear what causes SAD, but it’s thought that winter SAD may be caused by lack of sunlight. But this may not be the whole answer, as it’s also thought to run in families: 13–17% of people who develop SAD have an immediate family member with the disorder. 

https://cmha.bc.ca/documents/seasonal-affective-disorder-2/