Abstract

An intervention study was performed as a class (50 min for 136 junior high school students aged 13-14 years old) using a picture leaflet for junior high school students. The leaflet shows a detailed model day for “morning-typed student” versus “evening-typed one” based on several scientific evidences so far. An integrated questionnaire was administrated just before the intervention class and also one month after the class and the effects of class was evaluated. The questionnaire included the Diurnal Type Scale (DTS) which Torsvall and Ǻkerstedt (1980) constructed, and questions on sleep habits, mental health and breakfast contents. Among the students who occupied 75% as the morning- and medium typed populations before the intervention, students who increased the number of dishes at breakfast after the intervention class did not significantly shift their DTS scores (p=0.200), while students who did not change the number shifted their DTS scores to more evening-typed (p=0.012). Among ones who occupied 25% as evening-typed, students who increased the number of dishes significantly shifted their DTS to morning-typed (p=0.026), while ones who did not change the number did not change their DTS (p=0.893). In the whole, although the students experienced the intervention class, there were no significant effects to shift their diurnal rhythm into morning-typed direction, because the month after the intervention is the winter holidays (December-January). The intervention study may be effective for students to prevent the shift of their diurnal rhythm into “evening-typed”, even though the teacher of the intervention class has no previous knowledge on sleep sciences at all and study the leaflet for only 2 or 3 hours just before the class.

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