Sleep and circadian abnormalities
In a landmark study, Foster and colleagues compared the sleep-wake activity and circadian rhythms of 20 outpatients with schizophrenia (median duration of illness ten years) and 21 healthy controls over a period of six weeks.2 No patients and no controls were in paid employment.
“nature’s soft nurse” Shakespeare, in Macbeth
Despite the fact that patients were on newer antipsychotic medication and their symptoms relatively well controlled, sleep was of significantly poorer quality in patients than in controls, and more fragmented. On average patients with schizophrenia took 15 minutes more to fall asleep and slept two hours longer. Importantly for memory function, they showed less slow wave sleep than controls, and this may be relevant to poorer formation and consolidation of memory.
Compared with healthy subjects, patients had low levels of exposure to natural light, which may have impaired the setting of the internal clock, and the circadian melatonin rhythm in many was abnormal – suggesting lack of synchronisation between the external cycle of day and night and the body’s internal rhythm. Medication dose was not related to the extent of circadian abnormalities.
The fact that the control group was not employed suggests that lack of structured work does not account for the different sleep patterns of people with schizophrenia.