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

Objective Seasonal affective disorder (SAD) and the theory of the effect of light on depression have gained some popularity in recent years. Research on epidemiology is largely based on retrospective measures asking explicitly for the experience of seasonal variations. Those measures have a low positive predictive value and do not enable us to distinguish between experience and belief. Method A consecutive sample of chronic pain patients filled out a depression questionnaire (CES-D) routinely as part of the diagnostic interview on becoming 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 lig…