Objective. To investigate the relationship between insomnia, hemostatic abnormalities and silent cerebral infarctions. Material and methods. A complex study of 76 male patients, aged 40—85, with vascular risk factors was carried out. Magnetic resonance imaging (MRI) data was used to verify presence of silent cerebral infarctions; the presence and severity of insomnia were determined using questionnaires and polysomnography. Laboratory diagnosis included a complete assessment of hemostatic system with thrombodynamics test. Results. Patients were divided into 2 groups according the MRI data. The 1st group included 20 men with less than 4 silent cerebral infarctions, the 2nd group 56 men with multiple silent cerebral infarctions — from 5 to 25. Chronic insomnia was diagnosed in 35 (46%) of patients, more frequently in the second group (25% and 54% respectively, p<0.05). The group of patients with multiple silent infarctions demonstrated a loss of sleep efficiency and hypercoagulation with an increased rate of clot growth in thrombodynamics test. Correlation analysis confirmed the dependence between sleep efficiency and quantity of vascular sites, sleep efficiency and clot growth rate. Conclusion. The more severe plasma haemostasis disorder in patients with multiple silent infarctions and relation between insomnia severity and plasma haemostasis activation suggest that insomnia can be an additional risk factor of arteriole thrombosis.