Validation of the Munich ChronoType Questionnaire against actigraphy

Munich ChronoType Questionnaire (MCTQ) is a relatively new self-report instrument to measure chronotype and social jetlag. Despite its increasing use in research, validation studies against objectively measured circadian rhythm are scarce. This study aimed to analyze associations of the MCTQ parameters with those of restactivity cycle (indicator of sleep-wake rhythm) delivered from accelerometry. It was expected that: individuals representing later chronotype, as indicated by the MCTQ, show delay in the timing of activity and rest indicated by actigraphy; individuals experiencing greater social jetlag, as indicated by MCTQ, show less stable restactivity rhythm between days. A sample of 199 university students (79% women) aged 18–29 yrs (M=22.1, SD=1.7) completed MCTQ at the start of a seven-days actigraphy in home setting. Actigraph units (MotionWatch 8, CamNtech) were worn on a non-dominant hand continuously during the study period. Indicators delivered from MCTQ were: mid sleep on free days (MSF), which is the middle time point between sleep onset and sleep offset, representing chronotype, greater value means later chronotype; mid sleep on free days sleep corrected (MSFsc), which is MSF corrected for sleeping off on free days; social jetlag which is an absolute difference between MSF and mid sleep on work days, with higher values representing greater misalignment of biological and social time. Parameters of interest from actigraphy were calculated using nonparametric circadian rhythm analysis: least 5 start (L5 start) –clock time when the period of five least active hours starts; most 10 start (M10 start) –clock time when the period of ten most active hours starts; interdaily stability (IS) –higher values indicate more stable rhythm from day to day, lower values represent irregularity in rest-activity behavior. Pearson correlations indicated later MSF and MSFsc associated with later L5 start (r=0.20, p<0.01; r=0.20, p<0.01, respectively) and M10 start (r=0.50, p<0.001; r=0.44, p<0.001, respectively). Later MSF, but not MSFsc, was associated with lower IS (r=–0.15, p<0.05; r=–0.09, p=0.23, respectively). Greater social jetlag was associated with less stable rhythm as indicated by IS (r=–0.24, p<0.001), later M10 start (r=–0.15, p<0.05), but unrelated to L5 start (r=–0.05, p=0.48). Predictive value of MSFsc was not better than that of MSF regarding rest-activity rhythm. Self-reported “owls”, compared to “larks”, were delayed in the timing of objectively measured rest and activity. Social jetlag was observable in actigraphy. The results confirmed convergent validity of the MCTQ indicators.