Background/objective: Sleep is a critically important behavior which influences diverse aspects of health, functioning, and longevity. An increasing literature suggests the importance of sleep regularity, also referred to as sleep inconsistency, sleep variability, or intraindividual variability in sleep. Given there is no brief, subjective measure of sleep regularity, the purpose of this study was to develop the Sleep Regularity Questionnaire (SRQ) and to begin the process of examining its psychometric properties using a construct-validation approach.
Participants/methods: In an online study of sleep and health, participants (n = 3249; Mage (SD) = 42.77 (16.73); 48.5% female; 77.3% white) completed the in-development SRQ, as well as the Insomnia Severity Index and the Pittsburgh Sleep Quality Index.
Results: An exploratory factor analysis followed by a confirmatory factor analysis revealed a two factor structure, represented by circadian regularity and sleep continuity regularity, with good model fit indices (X2 = 50.9, df = 7, p < 0.001; RMSEA = 0.06; CFI = 0.99; NFI = 0.99; IFI = 0.99; TLI = 0.98). Test-retest reliability, as well as concurrent, convergent and incremental validity were examined, with promising results.
Conclusions: Preliminary psychometrics suggest that the SRQ is a valid and stable instrument for the assessment of sleep regularity in adults that is related to, but distinct from, other established sleep constructs. Future research will benefit from assessing the validity of the SRQ in various clinical samples and how it compares to measures of sleep regularity calculated from prospective daily assessments.
Keywords: Intraindividual variability; Measurement; Psychometrics; Self-report; Sleep inconsistency; Sleep regularity.
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