Definition: Winter depression 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 a small region of the brain (the suprachiasmatic nucleus). Its treatment is the use of a light box to artificially extend the day length.
Also Known As: Seasonal affective disorder, SAD
When she uses her light box each morning, she finds that her winter depression is better.