Affective Functioning, "Light Hunger," and Room Brightness Preferences

In this study, room brightness preferences of two groups of subjects were tested across an eight month period in a lighting simulation laboratory. Subjects were selected on the basis of their responses to the Seasonal Pattern Assessment Questionnaire (SPAQ) used by researchers to screen for seasonal affective disorder (SAD). One group of 10 subjects scored high on the SPAQ, indicating seasonal changes in mood and behavior. A control group matched on age and gender did not experience seasonal changes in any of the symptoms measured by the SPAQ. The study tested two hypotheses: (a) people with SAD are "light hungry" and should prefer a more brightly lighted room; and (b) if "light hunger" is seasonal, then the SAD group should prefer brighter light in the winter than in the spring months. Results indicate that the SAD group preferred a more brightly lighted room than did the control group across all testing sessions, thus supporting the first hypothesis. Because lighting levels did not differ significantly across the testing sessions, light hunger does not appear to be a seasonally expressed need. The SAD group had significantly higher levels of negative affect and depression across the testing sessions than did the control group. However, the SAD-like symptoms did not disappear in June, as expected. These findings suggest that (a) the SAD group did not, in fact, have SAD; or (b) testing did not occur long enough to measure mood and behavior changes. Results are discussed in terms of vulnerability to affective episodes and lack of light in the environment.