Objective: This study aimed to validate the Japanese version of the Restorative Sleep Questionnaire Weekly version (RSQ-W-J) and estimate the RSQ-W-J cut-off score to identify the degree of non-restorative sleep (NRS) that interferes with daytime function.
Methods: An online survey was conducted, and 513 participants (241 men, 272 women; mean age, 47.88 ± 16.66 years) completed the questionnaires. The RSQ-W-J, Multidimensional Fatigue Inventory, Athens Insomnia Scale, Patient Health Questionnaire-9, Epworth Sleepiness Scale, Sleep Debt Index, NRS and the degree of daytime dysfunction, and the diagnostic criteria for chronic insomnia were used as implementation scales.
Results: The RSQ-W-J was confirmed to have a single-factor structure. Both the Cronbach α coefficient and test-retest reliability of RSQ-W-J were high (α = 0.91; intraclass correlation coefficient [ICC]agreement = 0.85). The RSQ-W-J was significantly negatively correlated with the scales of fatigue, insomnia, depressive symptoms, daytime sleepiness, and sleep debt. In addition, the RSQ-W-J scores of the insomnia group, in which participants met the diagnostic criteria for chronic insomnia, NRS group, in which participants had NRS only, and sleep debt group, in which participants had sleep debt, were significantly lower than those in the normal sleep group. Furthermore, the insomnia group scored significantly lower than the sleep debt group. The RSQ-W-J cut-off score, which indicates whether or not NRS interferes with daytime function, was estimated to be 45.8 points.
Conclusions: The RSQ-W-J was shown to be useful for comprehensively measuring the degree of restorative sleep.
Keywords: Insomnia; Non-restorative sleep; Restorative sleep questionnaire; Sleep debt; Validation.
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