Circadian variations of self-reported activation: a multidimensional approach.

Self-reported activation measures through adjective checklist have not been widely tested in the field of chronopsychology. Previous studies have mostly explored two daily measurements (morning/evening) and reported differences as a function of the time of day. The aim of this study is to determine whether the energetic arousal, tensional arousal and hedonic tone scales of the Matthews' inventory (UMACL) change the function according to the time of day (09(00), 13(00), 17(00) and 21(00)). We also test whether morningness, sex or personality factors influence the results. The sample consisted of 156 university students of age 17-28 years, 41 of whom were men and 115 women. When all the subjects are considered, all UMACL scales show significant differences according to the time of day. Subjects presented a fall in their energetic arousal and hedonic tone from morning to evening, while tensional arousal increased throughout the day. However, when individual differences are taken into account, only morningness influences energetic arousal and hedonic tone. Morning-type subjects show an earlier peak time than evening-type subjects in both scales. The use of adjective checklist measures has been shown to be a valid method of revealing Self-reported circadian variations, and to assess individual differences in terms of their circadian typology or morningness.