Clinical and polygraphical (EEG, EOG, EMG, ECG, REG) studies of nocturnal sleep and of the hemodynamics were carried out in 60 patients with dyscirculatory encephalopathy induced by hypertension and atherosclerosis. The findings obtained demonstrate that the clinical picture in these patients is always characterized by sleep disturbances which decrease the level of their diurnal wakefulness and their capacity for work. Hemodynamic disturbances responsible for sleep disorders are in turn maintained by the latter which leads to the formation of the vicious circle. This is also supported by the fact that compromized cerebral circulation causes changes in the activity of the structures involved both in sleep-wakefulness function and the regulation of the cerebral and systemic hemodynamics. Hence, deviations in the nocturnal sleep pattern attended with pronounced alterations in the cerebral hemodynamics may contribute to the development of acute disorders of the cerebral circulation. The authors recommend correcting not only the disrupted structure of sleep but also the cerebral circulation with relation to he sleep-wakefulness cycle.