Psychometric Properties of the Persian Version of Sleep Hygiene Index in the General Population

BACKGROUND Inadequate sleep hygiene may result in difficulties in daily functioning; therefore, reliable scales for measuring sleep hygiene are important. OBJECTIVES The purpose of this study was to assess the psychometric properties of the Persian version of the Sleep Hygiene Index (SHI). MATERIALS AND METHODS From April 2014 to May 2015, 1280 subjects, who were selected by cluster random sampling in Kermanshah province, filled out the SHI, Pittsburgh sleep quality index (PSQI), Epworth sleepiness scale (ESS), and insomnia severity index (ISI). A subset of the participants (20%) repeated the SHI after a four to six-week interval to measure test-retest reliability. Then, we computed the Pearson product-moment correlation coefficients of SHI against PSQI, ESS and ISI, to demonstrate the construct validity of the SHI. The factor structure of the SHI was evaluated by explanatory factor analysis. RESULTS The interclass correlation coefficient was 0.89, and SHI was found to have good test-retest reliability (r = 0.89, P < 0.01). The SHI was positively correlated with the total score of the PSQI (r = 0.60, P < 0.01), ESS (r = 0.62, P < 0.01) and ISI (r = 0.60, P < 0.01). Exploratory factor analysis extracted three factors, namely "sleep-wake cycle behaviors" (four items), "bedroom factors" (three items), and "behaviors that affect sleep" (six items). CONCLUSIONS The Persian version of the SHI can be considered a reliable tool for evaluating sleep hygiene in the general population.