Objective: Epidemiological studies suggested that poor sleep is a potentially novel risk factor for several health outcomes currently; however, there are no validated questionnaires that can systematically measure sleep parameters within these studies. We evaluated the reliability and validity of 17-item sleep factors questionnaire (SFQ), which was developed to comprehensively assess long-term sleep habits for the Jiujiang Breast Cancer Study (JBCS), Jiujiang, China.
Methods: The participants included 100 women aged 18-74years, who were randomly selected from the JBCS project, and completed a SFQ at baseline and again 1year later, and 4 quarterly 30 consecutive days (a total of 120days) sleep diaries over this same year. Reliability was tested by comparing the 2 SFQs; validity by comparing the average measures between the SFQ and the 4 sleep diaries.
Results: Validity analysis showed moderate correlation (γ=0.41) for sleep duration with the adjusted concordance correlation coefficient (CCCadj) of 0.54; the weighted κ statistics indicated an excellent agreement for night/shift work and sleep medication use; fair-to-moderate for sleep quality, light at night (LAN), nighttime sleeping with light on, sleep noise and nap time; slight-to-fair for sleep quality and nighttime wakings frequency. Reliability analysis showed excellent correlation for night/shift work and sleep medication use; fair-to-moderate for LAN, nighttime wakings frequency, insomnia frequency, sleep noise and nap time; but slight-to-fair for insomnia frequency and nighttime sleeping with light on; the CCCadj for sleep duration was 0.61.
Conclusions: The SFQ showed reasonable reliability and validity for sleep assessments in most domains.
Keywords: Reliability; Sleep duration; Sleep factors questionnaire; Sleep quality.
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