Sex differences in sleep after a single oral morning dose of olanzapine in healthy volunteers

Abstract

Polysomnography abnormalities are frequent in schizophrenia and have been correlated with clinical variables. Because women with schizophrenia present a general better clinical outcome than men, we aimed to determine whether sex differences in antipsychotic-induced effects on sleep could contribute to this difference. Single oral morning doses of olanzapine (5 mg) were administered to 10 men and 10 women. Sleep variables were evaluated using traditional polysomnography Rechstschaffen and Kales criteria and all-night sleep electroencephalogram spectral analysis. Drug plasma concentrations were also measured. Significant sex-by-drug interactions were obtained in slow-wave sleep. After olanzapine, women showed an increase in slow-wave sleep, whereas men showed a decrease. We did not observe sex differences in olanzapine-induced hypnotic effects. Neither did we find any significant differences in pharmacokinetic parameters between sexes. Significant sex effects were observed in deep sleep, with women showing longer periods than men. Our results showed significant pharmacodynamic differences in olanzapine sleep effects between men and women. Further studies in clinical populations are needed to assess if these sex-based differences suggest that optimal treatment and doses should differ between men and women.