Misalignments of rest–activity rhythms in inpatients with schizophrenia

Aims:  Rest–activity rhythms of human beings generally synchronize to a 24-h time cue. Very few detailed research studies have examined rest–activity rhythms in patients with schizophrenia. The present study aimed to explore (i) rest–activity rhythms in patients with schizophrenia, and (ii) factors relevant to their rhythm characteristics. Methods:  We selected only inpatients for this research, because the time cue for inpatients was considered more standardized than that of outpatients. Sixteen inpatients with schizophrenia wore an ActiTrac accelerometer-based activity monitor (IM Systems Inc., Baltimore, USA) for eight consecutive days to measure their activity. We used a χ2 periodogram to compute rest–activity rhythms from the activity data, whereby the χ2 value amplitude was regarded as an index of regularity. We conducted non-parametric tests to identify factors relevant to rhythm cycles and patterns. Results:  Half of the participants exhibited prolonged rest–activity cycles, and 25% also had irregular rest–activity patterns defined by insufficient χ2 value amplitude, even though they were clearly under a 24-h time cue. Participants with misaligned rest–activity rhythms had attended daytime non-medical treatment programs less frequently, and had received more anti-anxiety/hypnotic medications than those with proper rhythms. Conclusion:  Changes in rest–activity rhythms by optimizing pharmacological and non-pharmacological treatment could improve social adjustment or quality of life in patients with schizophrenia.