Intervention Study to Improve Meal Habit , Sleep Habit , Circadian Typology and School Marks in Japanese Elementary School Students

Purpose: An intervention program called “Super Meal Education Program” was supported by Japanese Ministry of Arts, Sports, Sciences and Education. This program was implemented to improve meal habit and sleep habit and also to improve academic marks at school by Japanese compulsory schools students. The effects of the intervention were evaluated by comparing an integrated questionnaire study held both before and after the intervention of a half year. Method: The intervention program consists of a lecture on sleep health and diurnal rhythms of children by an university professor, a series of lectures and practical classes by elementary school teachers on foods which can be collected nearby, and also practical courses as excursions to learn traditional meals and several foods resources which are products nearby. Integrated questionnaire study and also government official academic achievement test were performed before and after the intervention 6 months in May and November, 2015. An integrated questionnaire was administrated to elementary school students of grades 1 to 6 (7-12 years old). For the younger students aged 6-9 years old, parents (mostly mothers) answered the questionnaire instead of their children. The integrated questionnaire included questions on the diurnal type scale (DTS), sleep habits, meal habits, and other questions on their environments and habits. Result: The rate of answer to the questionnaire was more than 95% and the number of data was 295 before and 286 after the intervention. In the histogram on distribution of the diurnal type scale scores (DTS) before intervention, 25 % of evening-typed students significantly shifted to significantly more morning-typed persons after that (p<0.001). There was significantly negative correlation between DTS scores before intervention and the amount of increased change in DTS during the intervention period (r=-390, r<0.001). For all students in the elementary school, there were no significant changes in sleep quality, bedtime in weekdays, wake up time and sleep hours before and after the intervention period. There was negative correlation between sleep hours in weekday before intervention and increased amount in sleep hours before and after that (r=-0.545, p<0.001). The longer the sleep hours become during intervention, the better the academic achievement mark was after the intervention (students in the second, third and fifth grades: r=0.369, p<0.01) in mathematics mark. Conclusion: At least for the students who had been originally evening-typed, the intervention on meal habits may be effective for longer sleep hours and improved school achievement marking. DOI : 10.14302/ISSN.2574-4518.jsdr-16-1413 Freely Available Online www.openaccesspub.org | JSDR CC-license DOI : 10.14302/issn.2574-4518.jsdr-16-1413 Vol-1 Issue 1 Pg. no.43 Introduction In accordance with the 24 hours commercialization society which is rapidly going on in current Japanese society which gives children new environmental situations as zeitgebers. Convenient sores are very common in Japanese society and they count more than 20 shops in a small society with 300,000 population, Kochi city for example and smart phones distribute to 98% of junior high school students affiliated to Faculty of Education, Kochi University. Such current situation means that clear light-dark cycles and meals regularity on the times of day tend to disappear for the entrainment of their circadian clocks. According to such environments to children, night activity is supposed to be in progress and also lead to short night sleep hours due to late bedtime and early get-up time because of school and shifting to evening-typed life. Due to the circumstances for Japanese children, some intervention program is needed for promotion of physical and mental health of Japanese children. Mental health has strong links to circadian typology: lower mental health like as depression can be associated with evening-typed life [1-7]. Because the circadian typology links to mental health, some intervention might be effective for preventing some mental problems in children [8]. However, such intervention studies for small children attending elementary school or younger are limited to a few ones. Quach et al. [9] reported the intervention project called “Sleep Well Be Well”. This project included individual consultations for families of children aged 5-6 years who had night sleep problems on screening. Gruber et al. [10] reported a project called “Sleep for Success” to improve sleep health and academic achievement. This project was a whole-school intervention involving sleep education for children, staff and parents. The participants of this project were children aged 7-11 years. This project used objective and subjective measurements of sleep. Sleep duration was elongated, sleep efficiency was improved and sleep latency was shorten due to the intervention. Another effective intervention program called “ACES” was developed for sleep health of adolescents and younger children [11]. Participants of 9-10 years were chosen because of no daytime naps already in this age [12]. However, there have been only a few studies on an intervention study including breakfast intervention (recommendation of taking protein resources) to improve academic achievement together with elongation of sleep hours for small children attending elementary schools so far. This study challenges to promote the academic mark and sleep habits of small children attending a model elementary school in Japan. Participants and Methods Description of the Study Participants Including Number of Participants The integrated questionnaire and Government Academy Achievement Test held by Japanese Ministry of Education, Arts, Sports, Sciences and Technology were administered twice in May and November in 2015 to all students who attended an elementary school (33oN, 133oE) in Kochi Prefecture, Japan. Students of all grades of the 1st to 6th answered the integrated questionnaire. On the other hand, students in the second, third and 5th grades participated in the Government Academy Achievement Test. More than 95% of the students in this school, to which both of the integrated questionnaire and the Government Academy Achievement Test were administered, answered the both. The number of students who answered the integrated questionnaire was 40-55 in each of the first to the six grades of the elementary school. The questionnaire included, 1) Diurnal type score questionnaire (DTSQ) Torsval and Åkerstedt [13] constructed, 2) Questions on sleep habit (bedtime, wake-up time, sleep hours of both weekdays and Corresponding author: Tetsuo Harada, Laboratory of Environmental Physiology, Graduate School of Integrated Arts and Sciences, Kochi University, Kochi, 780-8520, Japan, Tel: +81-88-8448410. Fax: +81-88-8448453. Email: haratets@kochi-u.ac.jp

Due to the circumstances for Japanese children, some intervention program is needed for promotion of physical and mental health of Japanese children. Mental health has strong links to circadian typology: lower mental health like as depression can be associated with evening-typed life [1][2][3][4][5][6][7]. Because the circadian typology links to mental health, some intervention might be effective for preventing some mental problems in children [8].

Sleep Habits and Meal Timing in Each Grade of Elementary School Children
The rate of answer to the questionnaire was more than 95% and the number of data was 295 before and 286 after the intervention. Bed time and sleep hours in week days in the third grade students before the intervention became slightly but significantly earlier and longer, respectively after the intervention (Table 2) . In the fifth grade, sleep hours in weed ends were significantly longer after the intervention (Table 3). In the fifth grade, the circadian phase of time when students became sleepy was shifted earlier by 20 minutes after the intervention. In the other grades, there were no significant differences between before and after the intervention in sleep habits and meal timing.

Diurnal Type Scales and Intervention
The distribution of the diurnal type scale scores before the intervention was similar to that after it

Sleep Quality and Sleep Duration Improved During Intervention
In the first and fifth grades of the elementary school, students improved sleep quality after the intervention (Wilcoxon test: the first grade, z=2.218, p=0.027; the fifth grade, z=2.563, p=0.010) (Figure 4).
There was negative correlation between sleep hours in weekday before intervention and increased of sleep hours during the intervention (r=-0.545, p<0.001).

Sleep Hours and Academic Achievement of Japanese Language and Mathematics
Before the intervention, significantly and clear higher mark in academic achievement of Japanese language appeared in the students who had more than 9 hours sleep than those who did less than 9 hours sleep

Discussion
The intervention program for a half year seems to be effective for elementary school students to take better mark in academic achievements especially on mathematics through shifting them to "morning-typed" life. How does the morning-typed life link to better academic achievement in elementary school students?
Three hypotheses would be possible as follows.
At first, sufficient REM sleep at the morning time          breakfast. The second one is that they should be exposed to sunlight after taking the nutritionally rich breakfast for serotonin synthesis. The third one is that they should be exposed to low temperature lights from night lighting for sufficient synthesis, at night, of melatonin from serotonin. These hormones work as natural anti-depression drugs (serotonin) and natural sleeping pills (melatonin) and function as inner zeitgebers for their circadian clock. They can finally make students more-morning typed and improve their mental health. The Higher serotonin level in daytime can be, the higher children's concentration on academic work at school is, leading to higher academic marks.

Conclusion
At least for the students who had been evening-typed, the intervention on meal habits may be effective for longer sleep hours and improved school achievement marking.