Exogeneity of the circaseptan mood rhythm and its relation to the working week

Previous longitudinal studies of mood showed that mood displays a circaseptan (weekly) rhythm, reaching its peaks during weekends and falling during the working week. These studies stirred numerous debates about whether the circaseptan nature of the mood is determined culturally or biologically. The goal of the present study was to determine how the division of the week on the working week and the weekend impacts mood. A sample of students completed the shortened version of the PANAS-X questionnaire each day throughout July (working week and the weekend not separated) and November (working week and the weekend separated). Cosinor rhythmometry was used to analyze the data. As in previous research, a circaseptan mood rhythm was detected in November. However, a circaseptan rhythm was not detected in July - a circasemilunar rhythm was detected instead. These results suggest that the division of the week on the working week and the weekend has a great impact on mood and that more longitudinal studies of this type are needed to better understand this relationship.