Seasonal Affective Disorder

September 26, 2011

Seasonal affective disorder (SAD) is a cycling and atypical mood disorder in which the symptoms get worse in winter when there are shortened days with lessened sunlight in temperate climates. It affects women more than men (about 80% are women) and is more common than one might expect with a prevalence of 1-3% of adults. The symptoms include mood changes, increased sleepiness, increased appetite with weight gain, a decreased interest in sex, lethargy and fatigue, all of which begin to increase as the daylight decreases in length. As many as 70% of women who have Seasonal Affective Disorder also have depressive symptoms associated with their menstrual cycle.

Comparing seasonal with nonseasonal depressions, researchers have found less employment and thinking impairment, less hopelessness, and weight loss with Seasonal Affective Disorder. Often anxiety symptoms accompany the depression. Researchers are also beginning to note some differences in biological and psychosocial aspects of Seasonal Affective Disorder such as gender, race, marital status, and employment. Individuals with bipolar I or II disease may also show some seasonality to their illnesses (i.e., worsening of symptoms with less light), although those with major depressive disorders usually do not. Men with Seasonal Affective Disorder have more obsessive/compulsive and suicidal symptoms than women. Those with dark-colored eyes with more pigment may suffer more than those with lighter colored eyes, which allow in more light.

Most of those with Seasonal Affective Disorder will respond to high-intensity light treatments (2,500 lux). This has given support to theories about the cause of seasonality to mood disorders being due to circadian rhythm disturbances, where the rhythms are delayed relative to the sleep/ wake and rest/activity cycle. If the circadian rhythm can be phase advanced by light, the individual with Seasonal Affective Disorder may show improvement in the troublesome symptoms. The latter are thought to be involved in the etiology as are theories about melatonin. Melatonin is a hormone that is produced by the pineal gland (in the brain), which may act as a coordinator between light exposure and circadian rhythms, which are related. Melatonin is a hormone which is involved in seasonal reproductive cycles in animals. While the causes are still elusive, treatments do include use of light therapy and aerobic exercise.

See Also: Bipolar disorder, Depression, Light therapy

Suggested Reading

  • Sadock, J. B., & Sadock, V. S. (2000). Comprehensive textbook of psychiatry (7th ed.). Philadelphia: Lippincott, Williams & Wilkins.

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