What is the Origin of Seasonal Affective Disorder?

The term was formally introduced into clinical psychiatry in the early 1980s by Dr. Norman Rosenthal and his research colleagues, who recognized and categorized the distinct, annually recurring pattern of mood disturbance. The name is descriptive, combining the seasonal timing with the affective (relating to mood) disorder (a state of illness). Its formal recognition provided a basis for targeted light-based therapies.

What is the Mechanism of Seasonal Affective Disorder?

The primary mechanism is thought to involve a significant misalignment of the body's internal circadian clock, the Suprachiasmatic Nucleus (SCN), due to the dramatically shorter photoperiods of winter. This light deficiency leads to a profound dysregulation of key neurotransmitters, most notably serotonin and melatonin. Specifically, there may be an overproduction or delayed clearance of melatonin, which promotes excessive sleepiness, and a reduction in serotonin activity, which is associated with mood elevation, resulting in the characteristic symptoms of lethargy and depression.

Seasonal Affective Disorder ∞ Area

Seasonal Affective Disorder

Meaning

Seasonal Affective Disorder (SAD) is a specific type of major depressive disorder characterized by recurrent episodes of depression that occur predictably in a distinct seasonal pattern, most commonly beginning in the late fall or early winter and spontaneously remitting in the spring and summer. This clinical condition is strongly linked to the profound reduction in natural sunlight exposure and the resulting significant disruption of the body’s circadian rhythm and neurochemical balance. It represents a failure of the human photoregulation system to adequately adapt to seasonal light changes.