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 chi(2) periodogram to compute rest-activity rhythms from the activity data, whereby the chi(2) 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 chi(2) 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.