Limits of self-report in assessing sleep terrors in a population survey

Sleep terrors are less frequent compared to other parasomnias, and there ar e no prevalence studies on adults We performed a questionnaire study in a w ell-defined population-based sample, the Finnish Twin Cohort. The study pop ulation consisted of 11,220 subjects aged 33-60 years, responding to questi ons on the frequency of sleep terrors in childhood and as adults. In the fi rst questionnaire about 9% reported sleep terrors often or sometimes in chi ldhood, and 3.5% at least once monthly as adults. However, in a second more -detailed questionnaire, only 1% of those with at-least-monthly attacks in adulthood presented with features compatible with the minimal diagnostic cr iteria for sleep terrors of the International Classification of Sleep Disor ders. There was also a strong correlation between current occurrence of nig htmares and the report of sleep terrors. Although a clinically definable en tity, sleep terrors seem to be unknown to lay people, at least in Finland. Therefore, the use of single items or brief question series on sleep terror s may give inaccurate results in questionnaires, An interview of a person w ho has witnessed the nocturnal attack suspected to be sleep terror is essen tial because of the patient's impaired recall of the episode. Our results a lso support the general View that sleep terrors are rare in adults.