Chronotype may play a role in the association between shift work and health risks. An important and widely used questionnaire for measuring chronotype is the Munich Chronotype Questionnaire for Shift workers (MCTQ); however, it has neither been validated nor is it available in Norwegian or any other Scandinavian language. Therefore, we translated the MCTQinto Norwegian and assessed its validity against subjective and objective sleep measures. We adhered to established methodological guidelines to translate the questionnaire. The final Norwegian version was administered to 60 workers (85% responders) on a three-shift schedule (21.7% women, median age 28 y) at an industrial plant. Sleep duration and mid-sleep from the MCTQwere compared with sleep diary and a multisensory sleep tracker (the Oura ring). Construct and criterion validity were evaluated. Sleep duration measured by the MCTQwas highly correlated ( > 0.6) with sleep duration calculated from both the Oura ring and sleep diaries after morning shifts. On free days, the MCTQcorrelated moderately with the sleep diary but weakly with the Oura ring. Mid-sleep correlations from MCTQcompared to the Oura ring data were high ( > 0.7) for sleep periods after morning and night shifts, and moderate ( = 0.5) sleep periods between free days following morning shift. Bland-Altman analyses indicated that the MCTQoverestimated sleep duration and underestimated mid-sleep, with the largest discrepancies on free days after morning shifts. Night shifts showed the most pronounced outliers. The Norwegian MCTQshows promising validity for assessing sleep habits in shift workers, particularly on workdays. However, reduced accuracy on free days after morning shifts suggests limitations in capturing sleep patterns across all shift types. Shift Shift Shift Shift Shift Shift Shift Shift r r r
