Stress in School. Some Empirical Hints on the Circadian Cortisol Rhythm of Children in Outdoor and Indoor Classes

Abstract

This prospective longitudinal survey compared the stress levels of students taught using an outdoor curriculum in a forest, with children in a normal school setting. We were especially interested in the effect outdoor teaching might have on the children’s normal diurnal cortisol rhythm. 48 children (mean age = 11.23; standard deviation (SD) = 0.46) were enrolled, with 37 in the intervention group (IG), and 11 in the control group (CG). The intervention consisted of one full school day per week in the forest over the school year. Stress levels were measured in cortisol with three samples of saliva per day. Furthermore, the data allowed for statistical control of physical activity (PA) values. For data analysis, we used a linear mixed-effects model (LMM) with random intercept and general correlation matrix for the within-unit residuals. The LMM yields that IG have expected greater decline of cortisol compared to CG; rate 0.069 µg/L vs. 0.0102 µg/L (log-units/2 h), p = 0.009. PA does not show a statistically significant interaction with cortisol (p = 0.857), despite being higher in the intervention group (p < 0.001). The main effect in our measures was that the IG had a steady decline of cortisol during the school day. This is in accordance with a healthy child’s diurnal rhythm, with a significant decline of cortisol from morning to noon. This effect is constant over the school year. The CG does not show this decline during either measurement day. Further research is needed to fully explain this interesting phenomenon.

Children&rsquo;s Cortisol and Cell-Free DNA Trajectories in Relation to Sedentary Behavior and Physical Activity in School: A Longitudinal Analysis

“…According to these analysis, the results of cortisol and cfDNA regarding the peak reactivity and AUCi are diverse. First, we could partially confirm our previously reported results [8] reflecting their independence of the analysis methodology, as students' cortisol levels were not affected by the relative amounts of MVPA in the IG. However, in the CG, the relative amount of MVPA is more likely to exert a lowering effect on the cortisol PR; the more active the students were in MVPA levels, the more their cortisol levels seemed to decrease.…”

“…However, we believe that our study can provide valuable insights into the EOtC research, health promotion in schools, and the assessment and analysis of cortisol, cfDNA, SB, and PA in the educational setting. In our previous study [8], we reported a statistically significant difference in the measured cortisol levels between the CG and IG; regular teaching in the forest correlated with a lower cortisol secretion at noon compared with the standard indoor teaching, and this association was independent of students' MVPA levels. Considering the compositional nature and, thus, the codependency of students' SB, LPA, and MVPA, we elucidated students' cortisol values during school time in this study.…”

“…The present paper aims to address these topics by investigating the relation between biological stress responses and physical activity in students taught in different school settings. Here, we extend our original investigation [8] by increasing our set of dependent variables and introducing cell free DNA (cfDNA) as an innovative biological marker, sedentary behavior (SB) and light physical activity (LPA) as more differentiated measures of physical activity and by applying sophisticated statistical models to better describe relations between our measures.…”

“…Overall, the existing knowledge on effects of EOtC is limited, despite the mentioned potentials of this type of teaching setting. In our recent publication [8], we compared the cortisol levels of students taught by applying an outdoor curriculum in the forest with children taught in the standard school setting; We were primarily interested in assessing the effect of outdoor teaching on children's normal diurnal cortisol rhythms. We reported that students in the intervention group (IG) exhibited a steady decline of cortisol levels during EOtC, whereas no such effect was observed in students in the CG during regular school days; in fact, the effect was independent of students MVPA levels.…”

De quelles preuves scientifiques disposons-nous concernant les effets des forêts et des arbres sur la santé et le bien-être humains ?

“…La recherche sur l'enseignement en dehors de la salle de classe -une technique d'enseignement intégrant périodiquement la nature, mise au point en Scandinavie [11,68] est unanime pour dire que dans les environnements naturels, cette méthode favorise invariablement des niveaux d'activité physique modérée à vigoureuse plus élevés, comparée aux méthodes classiques en salle [30,49,91,92,138]. De plus, on observe que le taux de cortisol chez ces enfants (indicateur de stress) diminue au cours d'une journée d'enseignement de ce type dans un environnement naturel, alors qu'il demeure inchangé sur une journée d'enseignement classique en salle [30].…”