Perceived quality of life in schizophrenia: relationships to sleep quality

We examined the relationship between perceived quality of life (QOL) and subjective quality of sleep among schizophrenia patients, and its relation to symptom severity, side effects and emotional distress. One hundred and forty five schizophrenia patients were comprehensively evaluated with standardized measures of symptom severity, adverse effects, emotional distress, QOL, and sleep quality (the Pittsburgh Sleep Quality Index, PSQI). Partial correlation and multiple regression analyses were performed. Poor sleepers reported lower mean scores on all QOL domains, they were more depressed and distressed, and had more adverse effects to medications with concomitant distress than good sleepers. The negative relationship between complaints of poor sleep quality and QOL measures remained significant when the confounding effect of depression, side effects, and distress was partialled from the correlation matrix. Daytime dysfunction (a component of the PSQI) accounted for 12.6% of the variance in QOL index scores. Thus, poor QOL reported by schizophrenia patients is substantially associated with poor sleep quality. This association appears both independently and synergistically with depression, distress and side effects of medications.