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).