Horne-Ostberg morningness-eveningness questionnaire (MEQ)

The MEQ is one of the most widely used and best validated tools for measuring diurnal preference [16]. It consists of 19 multiple-choice items, producing a score ranging from 16 to 86, with high scores indicating morning preference and low scores indicating evening preference. The initial chronotype cut-off points were validated for a population of young students, and as chronotype is strongly influenced by age and social factors, validated cut-off points for a middle-aged, non-shift working population have later been made [17]. We had no control group of our own for these data, but compared the results with a recent Danish study, chronotyping 275 CH patients and 145 controls [1]. The authors kindly provided chronotype distribution in the Danish populations adjusted for age (private correspondence).