What is seasonal affective disorder?
Seasonal affective disorder (also called SAD) is a type of depression that is triggered by the seasons of the year. The most common type of SAD is called winter-onset depression. Symptoms usually begin in late fall or early winter and go away by summer. A much less common type of SAD, known as summer-onset depression, usually begins in the late spring or early summer and goes away by winter. SAD may be related to changes in the amount of daylight during different times of the year.
How common is SAD?
Between 4% and 6% of people in the United States suffer from SAD. Another 10% to 20% may experience a mild form of winter-onset SAD. SAD is more common in women than in men. Although some children and teenagers get SAD, it usually doesn't start in people younger than 20 years of age. For adults, the risk of SAD decreases as they get older. Winter-onset SAD is more common in northern regions, where the winter season is typically longer and more harsh.
Written by familydoctor.org editorial staff