title: The Munich ChronoType Questionnaire for Shift-Workers (MCTQShift).
abstract: Sleep is systematically modulated by chronotype in day-workers. Therefore, investigations into how shift-work affects sleep, health, and cognition may provide more reliable insights if they consider individual circadian time (chronotype). The Munich ChronoType Questionnaire (MCTQ) is a useful tool for determining chronotype. It assesses chronotype based on sleep behavior, specifically on the local time of mid-sleep on free days corrected for sleep debt accumulated over the workweek (MSFsc). Because the original MCTQ addresses people working standard hours, we developed an extended version that accommodates shift-work (MCTQ(Shift)). We first present the validation of this new version with daily sleep logs (n = 52) and actimetry (n = 27). Next, we evaluated 371 MCTQ(Shift) entries of shift-workers (rotating through 8-h shifts starting at 0600 h, 1400 h, and 2200 h). Our results support experimental findings showing that sleep is difficult to initiate and to maintain under the constraints of shift-work. Sleep times are remarkably stable on free days (on average between midnight and 0900 h), so that chronotype of shift-workers can be assessed by means of MSF-similar to that of day-workers. Sleep times on free-days are, however, slightly influenced by the preceding shift (displacements <1 h), which are smallest after evening shifts. We therefore chose this shift-specific mid-sleep time (MSF(E)) to assess chronotype in shift-workers. The distribution of MSF(E) in our sample is identical to that of MSF in day-workers. We propose conversion algorithms for chronotyping shift-workers whose schedules do not include free days after evening shifts.
authors.affiliation: Institute of Medical Psychology, Centre of Chronobiology, LMU, Munich, Germany.
authors.forename: Myriam
authors.initials: M
authors.lastname: Juda
authors.forename: Céline
authors.initials: C
authors.lastname: Vetter
authors.forename: Till
authors.initials: T
authors.lastname: Roenneberg
mesh_terms: D000328:Adult; D000465:Algorithms; D001683:Biological Clocks; D002940:Circadian Rhythm; D005260:Female; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D012890:Sleep; D011795:Surveys and Questionnaires; D013997:Time Factors; D014851:Wakefulness; D014940:Work Schedule Tolerance; D055815:Young Adult