Assessing Resilience to Sleep Loss Among the Italian Population: A 13-Item Model of the Iowa Resistance to Sleeplessness Test (iREST)

Purpose: The present study aimed to validate the Italian version of the Iowa Resistance to Sleeplessness Test (iREST), a 16-item self-report assessing resilience to sleep debt in the affective, cognitive, and somatic domains. Participants and methods: We examined its factor structure, assessed internal consistency and criterion validity, and established test-retest reliability on 768 Italian native speakers (65.8% of women) with a mean age of 25.98 years old. Results: Confirmatory factor analysis (CFA) revealed a new 13-item structure for the Italian iREST (iREST-13), demonstrating more satisfactory goodness-of-fit values, and exhibiting good internal consistency (Cronbach's α ranging from 0.73 to 0.89), relative to the 16-item original version. Results supported the iREST convergent validity, showing significant independence from established measures of sleep; low correlations with conceptually unrelated measures supported divergent validity, indicating that the iREST effectively measures resistance to sleeplessness without confounding with other constructs. Lastly, test-retest reliability was evaluated by administering the iREST to the same sample with a 2-week interval: the significant correlations supported its temporal stability. Conclusion: Further studies are needed to evaluate the applicability of the iREST in diverse populations and explore its relationship with objective sleep measures. Nevertheless, the Italian iREST provides a valuable tool for assessing resistance to sleep loss, offering insights into individual differences in resilience. Additionally, the iREST can assist in identifying individuals who require interventions to enhance resilience to sleep debt, as well as help clinicians evaluate the impact of chronic sleep disruption and deliver targeted interventions.