Morningness-eveningness and sleep habits among adolescents: age and gender differences.

Previous research has indicated the need to use large samples in different cultural contexts in order to clarify age and gender differences on morningness-eveningness and sleep habits. The goal of our research was to study the relationship between morningness-eveningness and sleep habits in a large sample of 2,649 adolescents between 12 and 16 years. The Morningness- Eveningness Scale for Children and an adaptation of the School Sleep Habits Survey measures were used. Results indicated a greater tendency toward eveningness with age and higher eveningness in 13- and 14-year-old girls. Older adolescents claimed later rising time on weekends, later bedtime and shorter sleep length, and greater social jetlag, weekend rise time delay, and weekend bedtime delay. Girls reported earlier rising time on weekdays, later rising time on weekends, longer sleep length on weekends, and greater social jetlag and weekend rising time delay. Lastly, evening oriented adolescents claimed later rising time and bedtime, shorter sleep length on weekdays but longer sleep duration on weekends, and greater social jetlag, weekend rising time delay, and weekend bedtime delay.