Stress and sleep in Kindergarten children: Predictors of psychiatric morbidity?

Within recent years altered hypothalamic-pituitary-adrenocortical (HPA) system and sleep regulation have reached considerable attention in psychiatry. The issue if these abnormalities contribute to the identification of high-risk subjects early in life still warrants clarification. Thus, a cross-sectional and longitudinal study was started in Kindergarten children.

102 five-year old children (59 boys, 43 girls) were enrolled in the examination of (1) basal (morning cortisol after awakening) and stress-challenged (standardized psychological stress test) HPA system activity assessed by saliva cortisol measurements and (2) sleep regulation investigated by actigraphy over 7 days.

Basal HPA system activity was significantly increased in girls when compared to boys (p<0.001) and predicted a high hormonal stress-related response with females showing higher values than males (p<0.01). Increased HPA system activity was significantly associated with hyperactivity/impulsivity and emotional problems (p<0.01). Sleep recordings revealed severe disturbances in up to 15% of the children with no gender difference. Particularly these subjects had significantly increased morning cortisol values when compared to good sleepers (p<0.05).

The present results in children point to a possible occurrence of neurobiological abnormalities already early in life. Prospective long-term follow up of these subjects will clarify if these markers are predictive for the onset of psychiatric disorders.