Subchronic effects of olanzapine on sleep EEG in schizophrenic patients with predominantly negative symptoms

Background: It is well known that sleep disturbance is an integral symptom of schizophrenia. In recent studies, a deficit of delta sleep has been observed in schizophrenic patients. Antipsychotic drugs with serotonin (5-HT2) receptor-antagonistic properties are considered to have delta sleep promoting effects. We have investigated the effects of subchronic olanzapine treatment on sleep EEG in schizophrenic patients. Methods: The effects of administration of olanzapine (15 to 20 mg) on sleep were studied for four weeks in 10 male, drug-free patients suffering from schizophrenia with predominantly negative symptoms. Conventional sleep EEG parameters were investigated at baseline and after treatment with olanzapine for four weeks. Additionally, spectral power analysis of the EEG signal in distinct frequency bands was computed for different sleep stages. Psychopathology (PANSS, HAMD-17, HAMA) and side effects were assessed weekly. Results: All patients improved, as measured by PANSS global scores. Compared to baseline, there was a significant improvement of parameters of sleep efficiency and an increase of delta sleep as well as REM sleep. Regarding spectral power values, no significant differences between baseline and treatment conditions were found. Conclusions: Sleep improvement was due to parameters of sleep efficiency and delta sleep, which may be related to serotonin antagonistic properties of olanzapine.