Is there a dissociative process in sleepwalking and night terrors?

The enduring and contentious hypothesis that sleepwalking and night terrors : are symptomatic of a protective dissociative mechanism is examined. This is mobilised when intolerable impulses, feelings and memories escape, withi n sleep, the diminished control of mental defence mechanisms. They then eru pt but in a limited motoric or affective form with restricted awareness and subsequent amnesia for the event. It has also been suggested that such pro cesses are more likely when the patient has a history of major psychologica l trauma. In a group of 22 adult patients, referred to a tertiary sleep dis orders service with possible sleepwalking/night terrors, diagnosis was conf irmed both clinically and polysomnographically, and only six patients had a history of such trauma. More commonly these described sleepwalking/night t errors are associated with vivid dream-like experiences or behaviour relate d to flight from attack. Two such cases, suggestive of a dissociative proce ss, are described in more detail. The results of this study are presented largely on account of the negative findings. Scores on the dissociation questionnaire (DIS-Q) were normal, alt hough generally higher in the small " trauma " subgroup. These were similar to scores characterising individuals with posttraumatic stress disorder. T his " trauma " group also scored particularly highly on the anxiety, phobic , and depression scales of the Crown-Crisp experiential index. Tn contrast the " no trauma " group scored more specifically highly on the anxiety scal e, along with major trends to high depression and hysteria scale scores. Tw o cases are presented which illustrate exceptional occurrence of later onse t of sleepwalking/night terrors with accompanying post-traumatic symptoms d uring wakefulness. It is concluded that a history of major psychological tr auma exists in only a minority of adult patients presenting with sleepwalki ng/night terror syndrome. In this subgroup trauma appears to dictate the su bsequent content of the attacks. However, the symptoms express themselves w ithin the form of the sleepwalking/night terror syndrome rather than as rap id eye movement sleep related nightmares. The main group of subjects with t he syndrome and with no history of major psychological trauma show no clini cal or Df S-Q evidence of dissociation during wakefulness. The proposition that, within the character structure of this group, the mechanism still ope rates but exclusively within sleep remains a possibility.