Seasonal affective disorders.

Seasonal affective disorders is a form of recurrent depression that appears to be precipitated by a specific stressor (i.e., winter) and resolves spontaneously in spring or summer. The elements of winter that must contribute to SAD are unknown at this time although light deficiency most likely plays a role. It is similar to late luteal dysphoric disorder because of the circumscribed time course, range of severity and female predominance. Atypical anergic symptoms usually dominate the clinical picture but more typical anxious and agitated symptoms can be present. Onset and offset of symptoms and severity varies greatly. Fall onset is usually gradual while spring remission can be more startling and abrupt producing hypomania in some patients. Full summer remission occurs in most patients when followed prospectively and is associated with improvement in personality and biological measures. Most patients improve with light therapy but it is not known how sustained this effect is or whether it is comparable to treatment with antidepressants in similarly affected patients. BL treatment also implies a single etiological mechanism of SAD, but this is still unproven. Lights, while effective do not appear to be as effective as summer. This could be because most BL clinical trials have been too brief to actually simulate summer or because of the significant heterogeneity in population. It is important to remember that lights alone cannot replicate summer conditions. Summer light is up to ten times stronger than currently available light boxes and the season produces many other environmental and social changes. Most likely SAD will prove similar to other forms of depression in that it is a multidimensional problem which requires a variety of treatments to alleviate various aspects of the syndrome.