The efficacy of transcranial electrostimulation for sleep-wake and behavior disorders in elderly patients with dementia was tested in a double-blind study. The subjects were 27 inpatients with multi-infarct dementia (12 males and 15 females, aged 58-86). They were randomly divided into two groups: active treatment (n = 14) and placebo treatment (n = 13). For electrostimulation, a device (HESS-100) was used which delivered repetitive rectangular electric pulses of 6-8 V at increasing frequencies from 6 to 80 Hz, each pulse lasting 0.2 ms and with a root mean square value of 256-530 microA. Electrostimulation was performed for 20 minutes from 10:00 h every morning. The active or placebo treatment was performed for 2 weeks in each group. The electrostimulation was significantly effective in behavior disorders such as wandering or nocturnal delirium, and decreased motivation during the daytime. It was also effective in improving night sleep. Electroencephalograms confirmed increased vigilance levels in the daytime both during and after the treatment.