Background: The present study aimed at studying the morningness-eveningness
chronotype (MEC) of daily and weekly biorhythm fluctuations in the aggression
of preschool children.
Methods: This was a causal-comparative study. The statistical population was
preschool children in Tehran. One hundred children were selected through
purposive sampling. They were examined at different times of day (08:00,
10:00, 13:00 and 15:00) and different days of the week (Saturday, Sunday,
Monday, Tuesday and Wednesday). The data collection tool used was the MEC
questionnaire for children, a behavioral questionnaire for preschool children
and a self-report questionnaire about aggression. The data was analyzed using
mixed ANOVA.
Results: The results showed that the aggressive behavior of pre-school children
in the educational environment varies throughout the day and week. Also, the
aggressive performance of preschool children in the morning differed from that
of mid-session children or evening-type children in the educational environment
during the week (P<0.01).
Conclusion: The results of the behavioral questionnaire showed that the effect of
the group on the level of aggression was not significant, but the effect of the day
of the week and time of day was significant
