Seasonal Affective Disorder (SAD)

Seasonal Affective Disorder (SAD) (also known as Major Depressive Disorder with seasonal pattern in the DSM-5) is a subtype of depression related to mood changes that are linked to seasonal changes. The diagnostic specifier “with seasonal pattern” can be describe a seasonal pattern of symptoms in both major depressive disorder and bipolar disorder.

This specifier applies to the lifetime pattern of mood episodes. The essential feature is a regular seasonal pattern of at least 1 type of episode (i.e. - mania, hypomania, or depression). The other types of episodes may not follow this pattern. For example, an individual may have seasonal manias, but his or her depressions do not regularly occur at a specific time of year.

Criterion A

There has been a regular temporal relationship between the onset of manic, hypomanic, or major depressive episodes and a particular time of the year (e.g. - in the fall or winter) in bipolar I or bipolar II disorder. Do not include cases in which there is an obvious effect of seasonally related psychosocial stressors (e.g. - regularly being unemployed every winter).

Criterion B

Full remissions (or a change from major depression to mania or hypomania or vice versa) also occur at a characteristic time of the year (e.g. - depression disappears in the spring)

Criterion C

In the last 2 years, the individual’s manic, hypomanic, or major depressive episodes have demonstrated a temporal seasonal relationship, as defined above, and no non-seasonal episodes of that polarity have occurred during that 2-year period.

Criterion D

Seasonal manias, hypomanias, or depressions (as described above) substantially outnumber any nonseasonal manias, hypomanias, or depressions that may have occurred over the individual’s lifetime.

This specifier can be applied to the pattern of major depressive episodes in bipolar I disorder, bipolar II disorder, or major depressive disorder, recurrent. The essential feature is the onset and remission of major depressive episodes at characteristic times of the year. 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 often characterized by prominent energy, hypersomnia, overeating, weight gain, and a craving for carbohydrates. It is unclear whether a seasonal pattern is more likely in recurrent major depressive disorder or in bipolar disorders. However, within the bipolar disorders group, a seasonal pattern appears to be more likely in bipolar II disorder than in bipolar I disorder. In some individuals, the onset of manic or hypomanic episodes may also be linked to a particular season.

The prevalence of winter-type seasonal pattern appears to vary with latitude, age, and sex. Prevalence increases with higher latitudes. Age is also a strong predictor of seasonality, with younger persons at higher risk for winter depressive episodes.

  • Light therapy is indicated as a first-line treatment of depression with seasonal affective subtype
  • The standard intensity of light needed is usually 10,000 lux (light intensity) for 30 minutes per day in the early morning for a period of 6 weeks.[1]
  • Bupropion has been shown to be effective in the prevention of SAD by starting treatment prior to the winter season.[2]