Psychophysiological differences between 16 patients with primary insomnia, 7 men and 9 women, of mean age 40.8 years, and 16 controls, matched according to age, sex and education, were studied. Insomniacs differed from controls in the following results: their motor activity level was higher during night, sleep efficiency was lower and complexity in slow wave sleep was higher. The Hyperarousal Scale score was higher in insomniacs and it correlated with severity of insomnia in Athens Insomnia Scale. Sleep latency in MSLT was not shorter in patients group. Reaction time was shorter, moreover, the number of presentations necessary to memorize all items of Selective Reminding Test was greater in these patients. Degree of the learning disturbance correlated with the Athens Insomnia Scale score. No correlations were found between Selective Reminding Test and standard polysomnographic parameters. To sum up, the hypothesis on 24-hour hyperarousal in primary insomnia has been confirmed and learning impairment has been documented in the present study, independent of standard polysomnographic parameters.