Seasonal affective disorder and exercise treatment: a review

In recent years, there has been considerable improvement in the diagnostic criteria and epidemiology of seasonal affective disorder (SAD). This condition is a cyclically recurring mood and neuro-vegetative disorder that particularly affects populations residing in northern latitudes. It is characterised by regular depressive episodes in the autumn and winter, and non-depressive periods in the spring and summer. To date, the aetiology of SAD has not been identified. The leading hypotheses include seasonal variation of the photoperiod, circadian phase shift and neurotransmitter dysfunction. A number of recent studies suggest that physical exercise may provide an effective and easily accessible treatment for patients suffering from SAD. Despite growing research efforts, the palliative effects of exercise on depression and seasonal mood disorders are not clearly understood. This review assesses the clinical and physiological evidence which suggests that exercise intervention may facilitate effective treatment for SAD. Particular emphasis is given to circadian mechanisms that have been hypothesised to explain mood-enhancing affects of physical exercise.