The Iowa Resistance to Sleeplessness Test (iREST).

INTRODUCTION: Despite considerable individual differences in the vulnerability vs resistance to effects of sleep loss, there is no practical self-report tool to predict these differences across domains and only limited evidence whether they are general or domain-specific. To address this need, we developed the Iowa Resistance to Sleeplessness Test (iREST). METHODS: A construct-validation approach was employed. During the substantive phase, self-report items were generated to capture vulnerability vs resistance to sleep loss across various psycho-behavioral domains. During the structural phase, analyses identified the underlying factor structure and examined reliability of individual scale scores. Finally, the external phase used convergent and discriminant analyses to evaluate the factors in light of related sleep and personality measures, and tested criterion validity of the scale scores in predicting neurocognitive and affective responses to experimental sleep restriction (Total N = 1018). RESULTS: Analyses yielded discriminant and reliable scale scores that reflected resistance across cognitive, affective, and somatic responses, while also marking a general resistance factor. Convergent and discriminant probes revealed moderate associations of scale scores with daytime sleepiness and sleep-related distress, but small to negligible associations with other measures of sleep behavior, perceptions, and personality. Critically, criterion analyses yielded validity evidence for predicting cognitive and affective impairments in response to experimental sleep loss. CONCLUSION: Scores on the iREST show validity in capturing cognitive and affective resistance to moderate sleep loss among young adults, supporting its further exploration as a practical tool for predicting behavior due to lost sleep.