Aging and Sleep in Schizophrenia Patients and Normal Comparison Subjects

This study examined subjective and objective sleep and circadian rhythms in older patients with schizophrenia vs. older normal comparison subjects (NCs). For study 1, sleep questionnaires were administered semiannually to 48 schizophrenia patients and 53 NCs (age range = 45-79 for patients and NCs) at the University of California, San Diego Center for the Study of Psychosis in Older Adults. The relationship between change in sleep reports over two years and depression, age, gender, education and living situation were examined. These variables were related to changes in some sleep measures. Risk of reporting unsatisfactory sleep was greater for patients than NCs. Across groups more depression was associated with too little sleep, unsatisfactory sleep, insomnia and falling asleep unintentionally during the day. Women increased while men decreased time spent napping over the two years. Within patients, higher mean neuroleptic dose was associated with more symptoms suggesting sleep disordered breathing. In study 2, sleep/wake and light exposure were measured with wrist actigraphs which were worn for 72 hours by 28 schizophrenia patients and 28 matched NCs. Circadian (24-hour) activity rhythms were modeled using an extended cosine function. When maximum per-minute activity was examined, patients were awake more, slept more, had a lower percent sleep and had more awakenings than NCs at night. During the day patients slept more and were awake less than NCs. Patients had lower amplitude circadian rhythms. Less bright light exposure was associated with later circadian activity rhythm peaks and higher minima. Light exposure rhythms of patients were less regular than those of NCs. This is the first study comparing sleep and circadian rhythms of schizophrenia patients and matched NCs using both subjective and objective data. Objective actigraph recordings confirm subjective reports of disrupted nighttime sleep and low daytime alertness in patients with schizophrenia. Reported sleep/wake disruption was related to depression, across groups. Circadian rhythms were less robust in older schizophrenia patients relative to NCs. Further research should address treatment of sleep disturbances in schizophrenia by targeting both nighttime sleep and daytime activity. Interventions to improve circadian rhythms should be considered as well.