2.3. The morningness-eveningness questionnaire
The circadian type of participants was evaluated using MEQ, which was initially presented by Östberg and Horne (26). MEQ is a self-assessment questionnaire comprising 19 questions; the scores range from 16 to 86. The score weighting of the questions is not equal. This questionnaire describes five behavioral types: definitely morning type (70-86 scores), moderately morning type (59-69 scores), neither type (42-58 scores), moderately evening type (31-41 scores), and definitely evening type (31-41 scores) (27). The Persian form of MEQ’s validity and reliability have been established (α = 0.79) (28).