Definition

Seasonal affective disorder (SAD) is a form of depression (see depression entry) most often associated with the lack of daylight. The condition usually occurs in the extreme southern and northern latitudes from late fall to early spring.

Description

SAD occurs in parts of the world where days are very short during some seasons of the year. In Alaska and parts of Canada, for example, there may be no more than a few hours of daylight during the winter months. During these periods, some people may become very depressed. That condition is known as seasonal affective disorder, or SAD. When SAD occurs in the spring, when there is more daylight, it is sometimes called reverse SAD.

Though SAD is not officially listed as a mental disorder by psychiatrists, some authorities think as many as ten million Americans may be affected by the condition. Another...