Prevalence of different parasomnias in the general population

Abstract

Objective

To estimate lifetime and current prevalence (defined as having experienced the specific parasomnia at least once during the last 3 months) of different parasomnias in the general population. In addition, to study the relationship between the different parasomnias and gender, depressive mood, and symptoms of sleep apnea, insomnia and restless legs, as well as estimating the prevalence of having multiple parasomnias.

Methods

Population based cross-sectional study. One thousand randomly selected adults (51% female), 18 years and above, participated in a telephone interview in Norway.

Results

Lifetime prevalence of the different parasomnias varied from about 4% to 67%. For sleep walking lifetime prevalence was 22.4% and current prevalence 1.7%. For the other parasomnias, lifetime and current prevalence were as follows: sleep talking 66.8% and 17.7%, confusional arousal 18.5% and 6.9%, sleep terror 10.4% and 2.7%, injured yourself during sleep 4.3% and 0.9%, injured somebody else during sleep 3.8% and 0.4%, sexual acts during sleep 7.1% and 2.7%, nightmare 66.2% and 19.4%, dream enactment 15.0% and 5.0%, sleep related groaning 31.3% and 13.5%, and sleep-related eating 4.5% and 2.2%. Depressive mood was associated with confusional arousal, sleep terror, sleep-related injury, and nightmare. There were few associations between the parasomnias and gender and symptoms of sleep apnea, insomnia, and restless legs, respectively. About 12% reported having five or more parasomnias.

Conclusions

This is one of few population based studies investigating the prevalence of parasomnias. Several parasomnias were highly prevalent in the general population. The data need to be interpreted with caution due to methodological issues, i.e., low response rate and single questions.

Introduction

Parasomnias are undesirable physical events or experiences that occur during entry into sleep, within sleep, or during arousals from sleep [1]. The events are manifestations of central nervous system activation. They are divided into disorders of arousal (from non-rapid eye movement [NREM] sleep), parasomnias associated with rapid eye movement (REM) sleep, and other parasomnias. All parasomnias can be diagnosed based on subjective reports from the patient, parent or caregiver, except for REM sleep behaviour disorder where the diagnosis requires polysomnographic documentation [1].

The disorders of arousal (sleep walking, confusional arousal, and sleep terror) are commonly seen in children, but adults may also experience such parasomnias [1], [2], [3]. Although not included as separate entities in the International Classification of Sleep Disorders (ICSD-2), sleep talking, sleep related violence, and sexual behavior during sleep are considered to belong to this group, as these phenomena often are present together with the disorders of arousal [1], [4], [5], [6]. All these parasomnias occur most commonly in the early part of the sleep period and usually in connection with slow wave sleep. Individuals are usually amnesic or partially amnesic for the event the next day.

Nightmare disorder, REM sleep behavior disorder (RBD), and recurrent isolated sleep paralysis are included in the group of parasomnias associated with REM sleep [1]. These parasomnias usually occur during the latter part of the sleep period, where REM sleep dominates. It is common to remember the event the next day, in contrast to the amnesia following NREM parasomnias.

Several parasomnias are not associated with specific sleep stages and thereby considered in the group of other parasomnias. Examples of these are sleep related groaning, sleep-related eating disorder, exploding head syndrome, sleep related hallucinations, and sleep enuresis [1].

It is not uncommon for an individual to have more than one parasomnia [1], [7]. Sometimes it is difficult to distinguish between different parasomnias, i.e., confusional arousal and sleep terror. The disorders of arousal can be considered on a continuum [3], with confusional arousal on one end and sleep terror and agitated sleep related violence on the other. The “parasomnia overlap disorder” is used as a diagnostic entity when RBD is observed in association with NREM parasomnias [1]. Several parasomnias can emerge in close association with specific sleep disorders, especially obstructive sleep apnea [1], [8]. Furthermore, parasomnias have been found to be associated with mental disorders, especially in adults [2], [9].

The prevalence of many of the parasomnias is unclear since there are few population based epidemiological studies. Several authors report that different wordings of a question about parasomnia may lead to very different estimates [10], [11]. Interestingly, Nielsen recently reported that a nonspecific question about dream enacting behavior gave a prevalence of 35.9%, whereas more elaborate questions produced higher prevalence, ranging from 77% to 98% [11]. Nielsen et al. conclude that retrospective, simple questionnaires may nonetheless prove valuable as screening tools for parasomnias.

Our aims of the present study were to explore the frequency of parasomnias in the general population through a telephone interview with relatively nonspecific single questions and to study the associations with gender, depressive mood, symptoms of sleep apnea, insomnia and restless legs. Furthermore, we wanted to study how many parasomnias each individual reported and the interrelationship between the different parasomnias.