Circadian rhythms in schizophrenia
Patients with schizophrenia frequently complain of poor sleep and are commonly observed to shift their rest-activity cycle. Despite the introduction of new antipsychotic drugs, sleep-wake abnormalities remain a major complaint. Of the few previous studies undertaken, all have suggested that abnormal rest-activity or EEG sleep profiles in schizophrenic patients are associated with an increase in severity of psychotic symptoms, a decrease in cognitive performance, and poor psychosocial outcomes. Katharina Wulff and I, working with Eileen Joyce (UCL) and Derk-Jan Dijk (Surrey) have initiated a detailed study of this phenomenon. Our results show that the circadian timing of the sleep-wake profile and endocrine rhythms are either severely delayed or free-running with respect to time of day in patients with schizophrenia. This work is currently being prepared for publication. We feel that a greater understanding of circadian disturbance in schizophrenia will not only increase our understanding of the neurobiology and neurogenetics of the disorder, but also provide the substrate for the development of clinical and pharmacological interventions. This will improve rehabilitation potential and the quality of life of patients and their families. Future studies will address whether a correction of these sleep-wake abnormalities will result in a reduction in psychotic episodes and the abnormalities of neurocognition, emotion and social isolation that are intrinsic to the disorder (5).