Seasonal Affective Disorder (SAD)

Patients with Seasonal Affective Disorder tend to experience depressive symptoms during a particular time of the year, most commonly fall or winter. They often begin in October or November and remit in April or May. The symptoms of SAD, also known as "winter depression," are listed below.

• altered sleep patterns, with overall increased amount of sleep
• difficulty getting out of bed in the morning
• increased lethargy and fatigue
• apathy, sadness and/or irritability
• increased appetite, carbohydrate craving and weight gain
• decreased physical activity

Researchers believe that Seasonal Affective Disorder is caused by winter's reduction in daylight hours which desynchronizes the body clock and disturbs the circadian rhythms. Winter depression is usually treated by morning exposure to bright artificial light. By providing appropriately timed light exposure, the body's circadian rhythms become resynchronized and the symptoms of SAD resolve.

Although the most common form of recurrent seasonal depressions in northern countries is the winter SAD, researchers at the National Institute of Mental Health have uncovered a type of summer depression that occurs during June, July and August. Summer SAD tends to occur more in the southern states such as Florida, as well as in Japan and China. Summer depressives frequently ascribe their symptoms to the severe heat of summer, although in some instances the depressions may be triggered by intense light.