Morningness-eveningness and diurnal variations in self-reported mood.

Effects of differences in morningness-eveningness (M-E) on diurnal variations in self-reported mood were examined in 28 female subjects. M-E was determined by using Horne and Ostberg's questionnaire, and mood by Mackay and his colleagues' stress arousal checklist. Self-reported arousal showed the expected pattern of variation across the day and this was found to be a function of subjects' M-E score. However, self-reported stress showed no significant differences due either to time of day or to subjects' M-E score. This confirms the independence of the two mood scales.