Questionnaire and Intervention Study on Effects of Drinking Cows’ Milk at Breakfast on the Circadian Typology and Mental Health of Japanese Infants Aged 1 - 6 Years

Abstract

This study examines relationship between drinking cows’ milk at breakfast and several mental and physical characteristics (the diurnal type, sleep habits and mental condition as anger, out of control of emotion, irritation and depression) of Japanese small children aged 1 - 6 years old. A questionnaire study and an intervention one were performed in this study. An integrated questionnaire was administered, in July 2014 to 1112 participants attending one of 10 nursery school and 1 kindergarten located in Kochi (33 &deg; N, 133 &deg; E), Japan, and 582 parents (mostly mothers) which answered it instead of children (rate of answer: 51.9%). Intervention was done to 111 children attending the kindergarten. Seventy six parents answered the questionnaire which was administered 3 months after the intervention days of 21 (rate of answer: 51.9%). There are two contents of intervention, one is the distribution of cows’ milk for 21 days to be drunk at breakfast and another is the distribution of leaflet entitled “Go to bed early! Get up early! and Take nutritionally rich breakfast and cows’ milk!” just before the intervention. Just before the intervention, letter was distributed to 111 parents who were asked for their children to follow the contents of the leaflet and drink the cows’ milk distributed every day for the 21 days. Small children who drink cows’ milk at breakfast more than once per week and take nutritionally rich breakfast more than 4 times per week are more morning-typed than the other three groups in which children fit into one or none of the two issues of taking morning cows’ milk and rich breakfast ( p < 0.001). In this intervention study, there was positive correlation between the days when both cows’ milk and main dish (protein rich resource) were taken at breakfast and the diurnal type scores three months after the intervention period of 21 days (high implementation with morning type) (r = 0.416, p = 0.004). Also there was positive correlation between the implementation value for the 21 days and the diurnal type score 3 months later (r = 0.301, p = 0.018). Drinking cows’ milk at breakfast seems to be effective for small children to become more morning-typed through two sets of syntheses from tryptophan via serotonin into melatonin in the evening.