Seasonal depression or seasonal affective disorder (SAD) is a type of depression where the onset of depressive symptoms is triggered by seasonal changes. Seasonal depression is more common in people who live far north of or far south of the equator. Typically, this type of depression returns every fall/winter and lifts during spring when there is more natural sunlight. Some people experience a less common type of seasonal depression where the symptoms occur during spring and summer.
The severity of depressive symptoms can be divided into three categories: mild, moderate and severe depression. Mild depression: In the case of mild