Impact of sleep latency and efficiency on metabolic syndrome in schizophrenic patients

Objectives

Patients diagnosed with schizophrenia are known to have significantly reduced life expectancy compared to the general population, with approximately 60% of these premature deaths resulting from physical illnesses. A primary driver of this increased mortality is cardiovascular complications, which are closely linked to the high prevalence of metabolic syndrome (MetS) among schizophrenic patients. While it is well-established in the general population that sleep disturbances and circadian rhythm disruptions are associated with metabolic disorders, objective research focusing on this relationship within the schizophrenic population has been notably limited. Therefore, this study was designed to investigate the association between sleep quality, physical activity levels, and metabolic syndrome in chronic schizophrenic inpatients using objective actigraphic measurements.

Methods

This cross-sectional study included 101 chronic schizophrenic patients (based on DSM-IV-TR criteria) who had been hospitalized for more than two months at Naju National Hospital. Participants had a mean illness duration of approximately 26 years. Among the total sample, 54 patients (53.4%) met the NCEP-ATP III criteria for metabolic syndrome. Subjective assessments were conducted using the Pittsburgh Sleep Quality Index (PSQI) for sleep quality, the Epworth Sleepiness Scale (ESS) for daytime sleepiness, and the International Physical Activity Questionnaire (IPAQ) for physical activity. Objective data for sleep parameters and physical activity were collected over a seven-day period using an actigraph (ActiGraph WGT3X-BT) worn on the non-dominant wrist. Various sleep variables, including total sleep time, sleep latency, and sleep efficiency, were analyzed. Multivariate logistic regression analysis was performed to identify independent risk factors for metabolic syndrome, adjusting for variables such as age and gender.

Results

The study found significant differences in objective sleep parameters between patients with and without metabolic syndrome. Specifically, the MetS group exhibited significantly longer total time in bed (TIB) (p=0.032), prolonged sleep latency (p=0.001), increased wake after sleep onset (WASO) (p<0.001), and longer average awakening durations (p=0.015) compared to the non-MetS group. Furthermore, multivariate logistic regression analysis revealed that long sleep latency (OR 7.876, 95% CI 1.519–40.833, p=0.014) and low sleep efficiency (OR 9.902, 95% CI 1.111–88.220, p=0.040) were potent independent risk factors for the presence of metabolic syndrome. Interestingly, there were no significant differences between the two groups in terms of subjective sleep scales (PSQI, ESS), Morningness-Eveningness types, or overall physical activity levels as measured by both self-reports and actigraphy.

Conclusions

This research provides the first objective evidence using actigraphy to correlate sleep quality and metabolic syndrome specifically within a chronic schizophrenic population. The findings indicate that prolonged sleep latency and reduced sleep efficiency are strongly associated with metabolic syndrome, potentially mediated by the activation of the hypothalamic-pituitary-adrenal (HPA) axis and subsequent hormonal imbalances that trigger emotional eating and cardiovascular strain. These results emphasize the clinical necessity of prioritizing sleep management as a core component of therapeutic interventions aimed at reducing metabolic and cardiovascular risks in chronic schizophrenia. Despite limitations like the lack of polysomnographic data or total caloric intake monitoring, the study’s-controlled hospital environment and robust sample size strengthen the validity of these associations.

References

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