A. There has been a regular temporal relationship between the onset of major depres-
sive episodes in major depressive disorder and a particular time of the year (e.g.,
in the fall or winter).
Note:  Do not include cases in which there is an obvious effect of seasonally related
psychosocial stressors (e.g., regularly being unemployed every winter).
B. Full remissions (or a change from major depression to mania or hypomania) also
occur at a characteristic time of the year (e.g., depression disappears in the spring).
C. In the last 2 years, two major depressive episodes have occurred that demonstrate
the temporal seasonal relationships defined above and no nonseasonal major de-
pressive episodes have occurred during that same period.
D. Seasonal major depressive episodes (as described above) substantially outnum-
ber the nonseasonal major depressive episodes that may have occurred over the
individual’s lifetime.
Note:  The specifier “with seasonal pattern” can be applied to the pattern of major de-
pressive episodes in major depressive disor der, 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 remis-
sion of episodes must have occurred during at least a 2-year period, without any non-
seasonal 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 ex-
plained by seasonally linked psychosocial stressors (e.g., seasonal unemployment or
school schedule). Major depressive episodes that occur in a seasonal pattern are often