BACKGROUND: The relationship between physiological stress measures and body composition or behavioral problems in older children remains controversial, and data in young children are lacking. The aim of the study was to investigate this relationship in predominantly healthy preschool children.
METHOD: Physiological stress measures were assessed using diurnal salivary alpha-amylase (sAA) and salivary cortisol, nail cortisol and parasympathetic activation (PNS) by overnight heart rate variability, and body composition (body mass index, skinfold thickness) and behavior problems (using the Strengths and Difficulties Questionnaire) in 324 children aged 2-6 years of the SPLASHY study.
RESULTS: Parasympathetic nervous system was inversely related to body fat, to emotional, and to peer problems. Diurnal sAA was related to hyperactivity problems and moderated the relationship of cortisol and hyperactivity problems. Cortisol was not related to any other health problems.
DISCUSSION: The relationship of PNS with body composition and behavioral problems might highlight the protective role of the parasympathetic system early in life.