The impact of the changing seasons on mood and behavior (i.e., seasonality) has long been of interest to researchers. Recently, researchers have begun to look beyond biological explanations to investigate psychological variables that may play a role in the development of seasonal affective disorder (SAD) and subsyndromal (S-SAD) levels of seasonality. Rumination, in particular, has received initial support as a process that predicts more severe levels of winter depression. In the first study, we assessed the effects of rumination, current weather conditions, current level of depression, and attitudes toward weather conditions as predictors of seasonality. In addition to weather conditions, weather attitudes, and current depression, rumination emerged as a significant predictor of seasonality in females but not for males. In the second study, we followed individuals categorized as being high (S-SAD) and low in seasonality over time and assessed for depression at Time 1 and Time 2. Rumination, in addition to current weather conditions and weather attitudes, emerged as a significant predictor of depression for females in the S-SAD group. The results of these studies provide support for the role of rumination in seasonal depression, particularly for females. This type of research may contribute to attempts to better explain gender differences in seasonal depression.
