Definition: Seasonal affective disorder is a recurrent mood disorder associated with depression and excessive sleepiness during winter months. It is caused by a lack of bright light reaching the biological clock in the suprachiasmatic nucleus, a small region of the brain. Its treatment is the use of a light box to artificially extend the day length.
Also Known As: SAD, winter depression
Examples:
During the winter months I am tired all the time and depressed because of my seasonal affective disorder.
