This is a sub-disorder under Depressive Disorders and applies to a pattern of major depressive episodes that occurs in line with seasonal changes. Winter-type seasonal pattern is most-common, especially in higher latitudes.

The essential feature is the onset and remission of major depressive episodes at characteristic times of the year. Formerly known (DSM-IV) as Seasonal Affective Disorder (SAD), in most cases, the episodes begin in fall or winter and remit in spring. Less commonly, there may be recurrent summer depressive episodes.

This pattern of onset and remission of episodes must have occurred during at least a 2-year period, without any nonseasonal episodes occurring during this period. In addition, the seasonal depressive episodes must substantially outnumber any nonseasonal depressive episodes over the individual’s lifetime.

This specifier does not apply to those situations in which the pattern is better explained by seasonally linked psychosocial stressors (e.g., seasonal unemployment or school schedule).

Major depressive episodes that occur in a seasonal pattern are characterized by:

  • Prominent energy
  • Hypersomnia
  • Overeating
  • Weight gain
  • Craving carbohydrates

It is unclear whether a seasonal pattern is more likely in recurrent major depressive disorder or in bipolar disorders. Age is also a strong predictor of seasonality, with younger persons at higher risk for winter depressive episodes.

This entry has been adapted for DSM-5.