The present study explores the relationship between childhood maltreatment experiences and spectral power in high-frequency EEG activity during sleep in a sample of adults experiencing primary insomnia. Forty-five nontreated patients with primary insomnia spent three consecutive nights in the sleep laboratory, during which polysomnographic recordings were carried out. Nonrapid eye movement and rapid eye movement EEG data were analyzed using spectral analysis. In addition, each participant completed several self-report questionnaires assessing maltreatment in childhood and adolescence, current level of stress, and current depressivity. Insomnia patients with self-reported history of moderate to severe childhood maltreatment (MAL group; n = 25), as measured by the Childhood Trauma Questionnaire, were compared with insomnia patients without such a history (non-MAL group; n = 20). The MAL group exhibited more absolute and relative beta 1 and beta 2 power in nonrapid eye movement sleep and more absolute beta 1 and beta 2 activity in rapid eye movement sleep than the non-MAL group. Contrary to hypothesis, no group differences were found in gamma frequency band. The results suggest an association between history of childhood maltreatment and increased beta EEG activity particularly during nonrapid eye movement sleep in adult insomnia, what may reflect heightened psychophysiologic arousal during sleep.