Seasonal Affective Disorder
Many people may feel sad or down during the winter months, when the days are shorter and temperatures drop. For some people, this condition goes beyond the winter “blahs” and develops into a subtype of clinical depression that lasts throughout the late fall and winter months. This condition is known as seasonal affective disorder, or SAD. The term SAD was introduced in 1984 and has since been included in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders.
SAD is characterized by recurring, cyclic bouts of depression, increased appetite, and an increased need for sleep (Ford 1992; Magnusson 2003). It contrasts with most depressive disorders, which are characterized by sleep disturbances and diminished appetite (Magnusson 2005). Besides mild depression, typical symptoms of SAD include anxiety, decreased activity, social withdrawal, increased sleep duration, increased appetite, weight gain, and carbohydrate craving (Rosenthal 1984; Sher 2001).
SAD occurs in about 10% of the general population, although it is about twice as common among people treated for depression (Gross 1996). It tends to be more common in the higher latitudes, where winter days are comparatively shorter than at latitudes nearer the equator, and it occurs more often in women than in men (Rosen 1990; Gross 1996; Magnusson 2003). Studies have also shown that the tendency to develop SAD may run in families, which suggests a genetic component (Madden 1996). Family studies have shown that approximately 13 to 17% of people who have first-degree relatives with SAD will suffer from the condition themselves (Allen 1993; Thompson 1988; White 1990; Wirz-Justice 1986). The occurrence of SAD seems to lessen after the age of 55 years (Gross 1996).