Seasonal Affective Disorder

About Seasonal Affective Disorder

Seasonal affective disorder is a pattern of major depression, recorded in DSM-5 with the specifier with seasonal pattern, in which depressive episodes regularly begin and end at particular times of year. The winter pattern, starting in autumn or winter and lifting in spring, is far more common than the summer pattern, and prevalence tends to be higher at latitudes farther from the equator. It is diagnosed more often in women and commonly begins in young adulthood. Alongside typical depressive symptoms such as low mood, loss of interest and fatigue, winter pattern episodes often include oversleeping, increased appetite with craving for carbohydrates, weight gain and a heavy feeling in the limbs. The leading explanation involves reduced daylight affecting the circadian clock in the suprachiasmatic nucleus of the brain, along with changes in melatonin and serotonin signaling. The condition was described and named in the 1980s by the psychiatrist Norman Rosenthal and colleagues at the US National Institute of Mental Health. Bright light therapy using a special light box is a well established treatment, and cognitive behavioral therapy adapted for seasonal depression has also shown benefit. Antidepressants are used as well, and extended release bupropion is approved in the United States for preventing seasonal episodes. The role of vitamin D remains uncertain.