Detailed results for the sleep schedule and sleep duration, as obtained from the MCTQ and actigraphy, are presented in Figure 1 for free days and in Figure 2 for work days.
The corrected midpoint of sleep on free days as measured by the MCTQ and by actigraphy was also significantly and strongly correlated, and the means were also not significantly different.
Due to the wide range in the limits of agreement of the assessments of the two measures, the MCTQ cannot be used to estimate an objectively measured corrected of midpoint of sleep in an individual.
Therefore, for these other measures, the MCTQ, as with other subjective measures of sleep behavior, is prone to bias when compared to an objective measure such as actigraphy .
Thus, it may be interesting to compare how both the MCTQ and actigraphy compare to dim light melatonin onset.
A strength of this study, compared to previous ones using comparing the MCTQ with dim light melatonin onset [10, 23], is the larger sample size.
These findings support the use of the MCTQ to assess chronotype, but not to time treatment that requires a precise assessment of chronotype.
Caption: Figure 1: Means and standard deviations of MCTQ and actigraphy on free days.
Caption: Figure 2: Means and standard deviations of MCTQ and actigraphy on work days.