Seasonal affective disorder and seasonal depression are the same. The Seasonal affective disorder is the scientific term included under the broad category of major depressive disorders. Depression, on the other hand, is a severe form of M.D.D., where symptoms do not subside with changes in the weather or season. nSeasonal depression is diagnosed with two primary criteria:n1. Presence of seasonal depression symptoms for two consecutive years during the same time.n2. In case of overlap of general depression and seasonal depression, the episodes of seasonal depression may be more intense than non-seasonal depressive episodes.