No changes in mood with the seasons: observations in 3000 chronic pain patients

Objective: Seasonal affective disorder (SAD) and the theory of the effect o f light on depression have gained some popularity in recent years. Research on epidemiology is largely based on retrospective measures asking explicit ly for the experience of seasonal variations. Those measures have a low pos itive predictive value and do not enable us to distinguish between experien ce and belief. Method: A consecutive sample of chronic pain patients filled out a depressi on questionnaire (CES-D) routinely as part of the diagnostic interview on b ecoming in-patients at a Pain Clinic in Mainz during a 5-year period. Results: No support for seasonality or light effects was found. Conclusion: The effect of light on depression or seasonality may be smaller than expected in general. SAD as a true disorder is probably rare.