RESUMO
Persistent cognitive activity is an important factor in disturbing sleep-onset both during bedtime and when attempting to get back to sleep after nocturnal awakenings. One of the most specific self-report measures designed to assess this feature is the Glasgow Content of Thoughts Inventory (GCTI). In this study, we investigated the preliminary psychometric properties of GCTI in a large sample of higher education European Portuguese students (N = 2995). Our results suggest that there is evidence of good internal consistency (α = 0.93) and validity indicators. Moreover, we found an interpretable factorial structure comprising 5 correlated factors that needs to be confirmed in future studies. The European Portuguese version of the GCTI appears to be a reliable and valid instrument for measurement of sleep-onset disturbing cognitions.