Validation of the Morningness-Eveningness Scale for Children (MESC) with ambulatory circadian monitoring of temperature, light exposure and activity.

The external validity of the Morningness-Eveningness Scale for Children was analysed via objective measures of skin temperature, light exposure and motor activity with the ambulatory circadian monitoring methodology. A total of 138 adolescents (57 boys and 81 girls) aged 12-13 years, who in addition to completing the Morningness-Eveningness Scale for Children to determine their circadian typology wore a wrist activity device (Kronowise 3.0; Kronohealth SL) during school days and a weekend, participated. Circadian parameters, such as mesor, amplitude and acrophase, were estimated for skin temperature, light exposure and motor activity, as were sleep parameters, such as risetime, bedtime and social jetlag. The results indicated that during the weekend E-type adolescents experienced later acrophases in temperature, light and activity than I-type and M-type adolescents did, whereas boys experienced earlier acrophases in temperature and activity. When school weekdays were compared with the weekend, there was a weekend delay in the acrophases of temperature (1:03), light exposure (2:03) and activity (3:15). The results obtained in this study provide external validity for applying the Morningness-Eveningness Scale for Children in the naturalistic context of high school while considering sex and type-of-day differences as important variables in chronopsychological studies.