Because of sleep alterations in schizophrenia, 4 schizophrenic patients were studied to evaluate sleep-associated GH release. The GH night pattern was studied for 2 consecutive nights using a continuous blood sampling procedure, with simultaneous EEG, EOG, and EMG scoring. Sleep-related GH secretion was impaired in 3 out of 4 patients. No close correlation was evident between EEG sleep stages and GH secretion. Finally, correlations between biogenic amine disturbances in schizophrenia and GH night release impairment are discussed.