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STUDY OBJECTIVE: To determine correlates of morning and evening sleep-wake patterns in a community sample of children. DESIGN: A school-based cross-sectional survey. PARTICIPANTS: Sample included 1572 students, grades 4 to 8 (response rate, 98.4%), using a multistage sampling method. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Student participants completed a Sleep Habits Questionnaire, which included sleep schedules, a mood scale, substance use, the morningness/eveningness (M/E) scale, pubertal development scale, sleep disturbance scale, and parental monitoring scale. The morning (n = 367) and evening (n = 364) groups were operationally defined as participants who scored in the top or bottom 25% of the M/E scale, respectively. Linear mixed and tree-based classification models were used to explore correlates of sleep-wake patterns. Our results showed the evening type was associated with older school grade level, increased coffee drinking, moodiness, decreased parental monitoring, daytime sleepiness, and several sleep disturbances, including early insomnia, fear of sleeping in darkness, bedwetting, and going to bed later than 3 am. The 2 most potent discriminators between evening and morning subtypes were higher grade level, an index of age, and moodiness. The association of moodiness with the evening type was greater in boys than girls. CONCLUSIONS: These findings suggest that further research should address explanations for the association between evening type and mood and anxiety symptoms, including order of the effects, developmental factors, environmental determinants of sleep time such as school start time and parental bedtime monitoring, and circadian maturation.
Gau et al. (Sat,) studied this question.