Variation of behavioral and physiological variables in children attending kindergarten and primary school.

Twenty-one children aged 5-6 years (mean age: 71.2 months; S.D. = 2.7) were videotaped in 4 different kindergartens throughout the school day for a period of one week. Eighteen of these children were then followed up after the summer holidays and videotaped for one week while attending the first year of primary school. The behaviors measured for each child were yawning and general motor activity. It was found that: (1) The frequency of yawning appears to be 5 times higher in the first year of primary school than in the last year of kindergarten; (2) Throughout the school-day the percentage of yawning children is higher in the first year of primary school, with the exception of the 1400-1430 period; (3) In the first year of primary school, the percentage of yawning children and the frequency of yawning peak between 900 and 930 and 1430 and 1500; (4) In this school institution the percentage of children who get up from their chair and spontaneously move above increases from the beginning to the end of each school-day. Three cardio-vascular variables were investigated in 17 children of the sample population: heart rate, systolic and diastolic blood pressure. We found that: (1) The lowest values for heart rate in the first year of primary school are in agreement with the classical data of child development, as the children are 5-6 months older than in the last year of kindergarten. However, this is not the case at 1400 when the heart rate peaks at a higher level in the first year of primary school; (2) If the evolution in time of the blood pressure agrees in both institutions with the classical data of human chronobiology, i.e. the maximum values at 1400, the differences in mean level at all times during the school day between both institutions do not agree with what is commonly accepted, i.e. an increase in blood pressure with age; (3) The amplitude of the variations of the heart rate and blood pressure from one 30-min period to another throughout the school day is significantly higher in primary school. The comparison of the data obtained in both school institutions suggests that the observed differences are related to sharp modifications in school rhythms and constraints when the children go from the last year of kindergarten to the first year of primary school.