Date of Award


Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Doctor of Philosophy (PhD)




Sandra T. Sigmon

Second Committee Member

Bruce Hale

Third Committee Member

Marie Hayes


Historically, research on Seasonal Affective Disorder (SAD) has focused primarily on physiological hypotheses regarding etiology and maintenance. Recently research has also begun to investigate psychological and psychophysiological correlates of the disorder. The relation of activity level to SAD episode development, maintenance and recurrence, however, has not been investigated thoroughly. In this study, relationships between self-report (i.e., questionnaires and logs) and objective (i.e., actigraphy) measurements of activity and SAD were investigated. Also, the relationship between quantitative (i.e., number of activities or activity counts) and qualitative (i.e., activity enjoyment) aspects of activity and SAD were examined. It was hypothesized that individuals with SAD would experience activity levels that differed from those of controls. Various components of activity were examined (e.g., daytime activity, activity during sleep). In addition, the importance of activity enjoyment was also investigated. Individuals with a history of SAD (SAD-HX), individuals with a diagnosis of major depression (MDD), and controls were each assessed twice: in the winter and subsequent summer, or the summer and subsequent winter. At each measurement occasion, general depression symptoms, automatic negative thoughts, attitudes towards the seasons, motor activity levels, activity frequency and enjoyment of activities were assessed. In general, the results of this study supported the hypothesis that certain aspects of the activity patterns of individuals with a SAD-HX differ from those of controls. Although individuals with a SAD-HX did not differ from controls in objectively measured daytime activity, participants with a SAD-HX exhibited disrupted nocturnal activity patterns compared to controls. In addition, individuals with a SAD-HX differed from controls with regard to self-reported activities. Participants with a SAD-HX reported participating in fewer activities and enjoying these activities less than controls. The current study provides continued support for the contribution of cognitive factors that may relate to SAD episode recurrence and severity. Individuals with a SAD-HX exhibited patterns of negative thinking and styles of responding similar to individuals with major depression even during asymptomatic months. Implications of these findings for SAD research and treatment in general and for future SAD research are discussed.