Introduction Advancing age is accompanied by well- described changes in sleep pattern and increased prevalence of both sleep disturbances and cognitive impairment. Previous longitudinal studies exploring sleep and cognitive changes are scarce. Since disrupted sleep is linked to cognitive dysfunction, it remains an open question whether impaired sleep may be considered as an early sign of cognitive deterioration. The aim of this study was to examine whether objective sleep measurements are associated with subtle cognitive changes and cognitive performance. Materials and methods Overnight polysomnographic recordings were collected from 189 middle-aged males, recruited from the Project Metropolit 1953, as a part of a larger community-based prospective cohort study investigating predictors of minimal cognitive impairment. Based on earlier cognitive assessments, subjects entered the study as cognitively unimpaired (N =97) or cognitively impaired (N =92). A neuropsychological tests battery, including six paper–pencil tests, and Cambridge Neuropsychological Test Automated Battery (CANTAB) was applied. Results Cognitively impaired males showed lower sleep efficiency (78.54±12.82 vs. 83.14±10.56 p =0,02) and increased nocturnal wakefulness (17.23±6.97 vs.12.76±9.25, p =0,02) compared to cognitively unimpaired males. However, none of these measures showed significant group differences after Bonferroni correction. No correlation between sleep measures and cognitive scores was found. Conclusion These studies suggest that subtle cognitive changes seems to have, if any, relatively little influence on sleep per se. Future research is needed to study the heterogeneity of cognitive aging and potential predictors of cognitive decline. Acknowledgements Danish Centre for Sleep Medicine.