Evaluating sleep quality and daytime sleepiness in nursing students: psychometric validation of the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale

Background Sleep problems are common among nursing students, yet the psychometric performance of widely used measures remains underexamined. The Pittsburgh Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS) are frequently applied to assess sleep quality and daytime sleepiness, respectively, but evidence of their validity and reliability in nursing-student populations is limited. Aims This study aimed to evaluate the structural validity, reliability, and convergent validity of the PSQI and ESS in a sample of nursing students. Methods This methodological study was conducted among 368 nursing students enrolled at a university in Cali, Colombia. The Spanish versions of the PSQI and ESS were administered. In a subsample of 87 participants, a second assessment was conducted approximately eight weeks later to examine temporal stability. Item-level confirmatory factor analyses were conducted, internal consistency was assessed, latent variable correlations were examined via structural equation modeling, and test–retest reliability was evaluated using intraclass correlation coefficients (ICC). Results The theoretical unidimensional structure of the PSQI demonstrated poor model fit (CFI = 0.919; RMSEA = 0.137). In contrast, a respecified unidimensional model that included two residual correlations yielded substantially improved fit indices (CFI = 0.980; RMSEA = 0.065). For the ESS, a unidimensional model incorporating one residual correlation showed an acceptable fit (CFI = 0.997; RMSEA = 0.057). Both instruments exhibited satisfactory internal consistency, as evidenced by composite reliability (CR) coefficients of 0.774 and 0.904 for the PSQI and ESS, respectively. Their temporal stability was fair to moderate, as indicated by ICC of 0.464 for the PSQI and 0.567 for the ESS. Additionally, the structural model indicated a statistically significant correlation between the two scales (r = .721, p < .001). Conclusions The PSQI and ESS demonstrate adequate psychometric properties for assessing sleep quality and daytime sleepiness in nursing students. These findings support the use of both instruments mainly in nursing-student populations and comparable settings, helping to provide a more comprehensive evaluation of sleep health.