Sex differences in the cognitive performance in adults: role of impaired sleep

OBJECTIVE: Poor sleep quality negatively affects cognitive performance. However, there are limited data on sex differences in functional outcomes of impaired sleep on cognition. Therefore, the aim of this study was to evaluate the association between sleep quality and performance of men and women in cognitive tests. MATERIALS AND METHODS: After screening, 97 individuals with and without insomnia complaints participated of this study. Behavioral scales were evaluated using a number of instruments and the sleep pattern was recorded by actigraph. Subsequently, the participants were submitted to visuospatial/verbal working memory (WM), visual attention, and psychomotor vigilance tests (PVT). RESULTS: The actigraphic recordings indicated that men sleep later (d=-0.56, p<0.05), fall asleep faster (d=0.42, p<0.05), showed shorter sleep duration (d=0.53, p<0.05), and more sleep fragmentation than women (d=-0.41, p<0.05). The performance in the cognitive tasks also showed sex differences: the men showed better performance in the visuospatial short-term memory (d=-0.78, p<0.05); verbal (d=-0.61, p<0.05), and visuospatial-WM tests (d=-0.84, p<0.05); they also responded faster in the PVT (d=0.69, p<0.05), although made more mistakes (d=-0.85, p<0.01). Longer sleep latency was associated with poor performance in visual attention (r=0.52, p<0.05) and verbal memory tasks (r=-0.30, p<0.05) in men. CONCLUSION: Our results suggest that difficulty in falling asleep was associated with cognitive impairment, especially in men. Sex differences in sleep quality and cognitive skills should be taken into account in future research in this field