PURPOSE: Pharmacologic provocation test of growth hormone(GH) is a non-physiologic method and has several limitations for diagnosing growth hormone(GH) deficiency. Spontaneous GH release studies could be important in understanding the pathophysiology of children with poor growth but normal responses to GH provocation tests. Also, the relationship between nocturnal GH secretions and sleep patterns in short stature children is poorly understood. The aim of this study is to determine whether there are differences in sleep patterns and nocturnal GH secretory profiles between idiopathic short stature children and a normal stature group. METHODS: Spontaneous nocturnal GH secretions and sleep patterns were evaluated in 12 prepubertal idiopathic short stature children with normal responses to provocation tests and 9 normal stature controls. Blood samples were taken every 30 minutes from 22:00-06:30 and sleep patterns were analyzed by polysomnography. RESULTS: The mean GH level during sleep was significantly lower in short stature children than in controls. The peak GH level after sleep, coincident with the first slow wave sleep, was lower in the short stature group. The slow wave sleep times of short stature children were decreased compared with those of normal subjects. CONCLUSION: These results suggest that overnight serial GH sampling is helpful to identify short stature children with subnormal GH secretions, and sleep structure differences may be associated with decreased overnight GH secretions in short stature children.