Psychometric properties of the Spanish version of the Sleep Hygiene Index.

The Sleep Hygiene Index (SHI) has shown adequate psychometric properties in samples from several countries but has not been validated in Spanish. The aims of the study were to translate the original (i.e., English) version of the SHI into Spanish and to evaluate the psychometric properties of this instrument (i.e., factor structure, internal consistency reliability, and concurrent, predictive, and discriminant validity) in Spanish adults. The overall sample, comprising 548 university students, was divided into two groups based on their self-reported insomnia symptoms (Insomnia Severity Index) because sleep hygiene has been shown to be closely related to insomnia. The Pittsburgh Sleep Quality Index and the Stanford Sleepiness Scale were used for testing concurrent validity. The Depression, Anxiety, and Stress Scale was used for testing predictive validity. Three items were dropped from the original SHI scale due to their low factor loadings. The principal component analysis revealed a four-factor solution for the SHI, accounting for 65.58% of the total variance in the overall sample, for 65.34% in the noninsomnia group, and for 63.50% in the insomnia group. Factor 1 comprised items regarding sleep-disrupting behaviors; Factor 2 comprised items regarding cognitive activation; Factor 3 comprised items about bedroom comfort; and Factor 4 comprised items on sleep/wake time. Omega coefficient indices for the SHI ranged from 0.751 to 0.878 in the overall sample, from 0.734 to 0.822 in the noninsomnia group, and from 0.724 to 0.835 in the insomnia group. The Spanish version of the SHI can be regarded as a reliable tool with adequate concurrent and predictive validity for assessing sleep hygiene in Spanish people with or without insomnia symptoms.