Introduction: It was shown that subjective sleep problems in later life could be predictor of cognitive decline (Altena et al., 2010). Different modalities of cognitive functions were shown to be impaired – vigilance, working memory, motor control and motor learning. Materials and methods: Fifty patients with diagnosis of chronic insomnia disorder according ICSD-3 aged 59.0 ± 15.9 years, 45 females and 5 males, were studied with the battery of tests on cognitive functions. The following tests were used: Stroop for attention; clock drawing test for visuo-constructive abilities; Benton visual retention test for visual perception and visual memory; verbal fluency test for performance of semantic memory; trail making test (TMT) for visual attention and task switching. Disordered sleep was estimated by Insomnia severity index and clinical data. Results: Spearman rank correlation test revealed significant (p < 0.05) correlations between the results of Stroop task and sleep duration (r = −0.34), Benton test and number of awakenings (r = −0.53) and verbal fluency test and insomnia duration (r = −0.45). Mann–Whitney U test also revealed significant differences between results of Benton tests in patients with frequent (10.9 ± 2.2) and episodic (11.9 ± 2.1) night awakenings. Conclusion: We found very weak and inconsistent connection between the presence of any sleep disturbances in chronic insomnia patients and the results of cognitive function tests.