Prevalence of different parasomnias in the general population

Sleep Medicine 11 (2010) 1031–1034 Contents lists available at ScienceDirect Sleep Medicine journal homepage: www.elsevier.com/locate/sleep Original Article Prevalence of different parasomnias in the general population Bjørn Bjorvatn a,b,⇑, Janne Grønli b,c, Ståle Pallesen b,d a Department of Public Health and Primary Health Care, University of Bergen, Norway Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Norway c Department of Biological and Medical Psychology, University of Bergen, Norway d Department of Psychosocial Science, University of Bergen, Norway b a r t i c l e i n f o Article history: Received 18 March 2010 Received in revised form 30 June 2010 Accepted 13 July 2010 Keywords: Sleep talking Confusional arousal Sleep terror Sleep violence Sexsomnia Nightmare Dream enactment Sleep-related eating a b s t r a c t 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. Ó 2010 Elsevier B.V. All rights reserved. 1. 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 ⇑ Corresponding author. Address: Department of Public Health and Primary Health Care, University of Bergen, Kalfarveien 31, N-5018 Bergen, Norway. Tel.: +47 55 58 61 00; fax: + 47 55 58 61 30. E-mail address: bjorn.bjorvatn@isf.uib.no (B. Bjorvatn). 1389-9457/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.sleep.2010.07.011 also experience such parasomnias [1–3]. 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 [1,4–6]. 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]. 1032 B. Bjorvatn et al. / Sleep Medicine 11 (2010) 1031–1034 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. 2. Methods 2.1. Procedure Data were collected by a telephone interview conducted by an opinion-research institute (Norsk Respons), employing the next birthday technique. In the next birthday technique the interviewer asks to speak to the adult member of the household who has the next birthday. This technique constitutes a procedure of randomly selecting individuals within a household preventing potential selection bias [12]. The sample was drawn randomly from a survey population, consisting of Norway’s register of phone numbers. Phone numbers were called up to six times. In all, 3940 subjects were contacted, and 2940 subjects refused participation, thus, the response rate was 25.4%. The study was introduced by the interviewer as a university-based research project. The subjects agreed or declined to participate before being asked specific questions. Due to these procedures the survey was exempted from review by the Ethics Board (The Regional Committee for Medical Research Ethics in Western Norway). 2.2. Participants A total of 1000 randomly selected adults, stratified by the number of inhabitants in each county of Norway, agreed to participate in the study. In all, the sample consisted of 51% females, and the mean age was 47.0 years (SD = 17.7, range = 18–96 years). Table 1 Parasomnia questionnaire. 1. Have you ever experienced or been told that you have been sleep walking? 2. Have you ever experienced or been told that you have talked in your sleep? 3. Have you ever experienced or been told that you have woken up at night in a confusional state without remembering the event the next day? 4. Have you ever experienced or been told that you have woken up at night in terror without remembering the event the next day? 5. Have you ever experienced or been told that you have injured yourself during sleep? 6. Have you ever experienced or been told that you have injured somebody else during sleep? 7. Have you ever experienced or been told that you have performed sexual acts in your sleep? 8. Have you ever experienced nightmares in your sleep? 9. Have you ever experienced or been told that you have been acting out of a dream in your sleep? 10. Have you ever experienced or been told that you groan or moan in your sleep (snoring not included)? 11. Have you ever experienced or been told that you have eaten food in your sleep or at night without being hungry? daily)[13]. We defined current prevalence as having experienced the parasomnia at least once during the last 3 months. The following parasomnias were explored using a single question for each: sleep walking, sleep talking, confusional arousal, sleep terror, injured yourself during sleep, injured somebody else during sleep, sexual acts during sleep, nightmare, dream enactment, sleep related groaning (snoring not included), and sleep-related eating. Furthermore, the participants were asked questions about possible sleep apnea (‘‘During last 3 months, have you had breathing pauses or stopped breathing in your sleep?”), insomnia (‘‘During last 3 months, have you had difficulty falling asleep or maintaining sleep?”), restless legs (‘‘During last 3 months, have you had restless or crawling feelings in your legs in the evening or at night that improved with movement?”) and depressive mood (‘‘During last 4 weeks, have you felt depressed most of the day, or experienced diminished interest or pleasure in activities you usually enjoy?”). These questions were adapted from the Global sleep assessment questionnaire [14], but we used the same six-point scale as for the questions about parasomnia [13]. Sleep apnea was defined as reporting symptoms at least once a week; whereas for insomnia, restless legs and depressive mood, the criteria were having symptoms at least 3 days per week. 2.4. Statistics The data analyses were performed with SPSS version 15.0 (SPSS, Inc.). The results were weighted according to the population distribution of gender and age in order to correct for potential divergence between the sample and the distribution of age and gender in the general population. Differences in the lifetime prevalence of the different parasomnias and gender, symptoms of sleep apnea, insomnia, restless legs and depressive mood were explored using chi-square statistics. The interrelationships between the different parasomnias (lifetime prevalence) were explored with the phi coefficients. Significance level was set to 0.05. 3. Results 2.3. Material The participants were asked about lifetime prevalence (yes/no) of different parasomnias (Table 1). If yes, they were asked about the frequency of the parasomnia during the last 3 months on a six-point scale (never, less than once per month, less than once per week, on 1–2 nights per week, on 3–5 days per week, daily/almost Lifetime prevalence of the different parasomnias varied from about 4% to 67% (Table 2). Current prevalence was naturally lower, but still all parasomnias were reported at least once during the last 3 months (Table 2). Current prevalence and occurrence at least once a week varied from 0.0% (injured somebody else during sleep) to 6.0% (sleep talking) (Table 2). 1033 B. Bjorvatn et al. / Sleep Medicine 11 (2010) 1031–1034 Table 2 Prevalence of different parasomnias. Sleep walking Sleep talking Confusional arousal Sleep terror Injured yourself during sleep Injured somebody else during sleep Sexual acts during sleep Nightmare Dream enactment Sleep related groaning Sleep related eating Lifetime prevalence in percent (95%CI) Current prevalence (at least once during the last 3 months)(%) Current and occurring at least once a week (%) 22.4 (19.8–25.0) 66.8 (63.9–69.7) 18.5 (16.1–20.9) 10.4 (8.5–12.3) 4.3 (3.1–5.6) 3.8 (2.6–5.0) 7.1 (5.5–8.7) 66.2 (63.3–69.2) 15.0 (12.8–17.2) 31.3 (28.4–34.2) 4.5 (3.2–5.8) 1.7 (0.9–2.6) 17.7 (15.3–20.0) 6.9 (5.3–8.5) 2.7 (1.7–3.8) 0.9 (0.3–1.5) 0.4 (0.0–0.8) 2.7 (1.7–3.7) 19.4 (17.0–21.9) 5.0 (3.6–6.3) 13.5 (11.3–15.6) 2.2 (1.3–3.1) 0.6 6.3 1.8 1.0 0.3 0.0 0.4 2.8 0.2 4.2 0.4 Males reported more often having ‘‘injured yourself during sleep” compared to females (5.7% versus 2.9%, p = 0.031). Females reported more nightmares (72% versus 61%, p < 0.0005) than males. No other gender differences were found. Depressive mood was reported by 5.5% of the respondents. Confusional arousal (31% versus 18%, p = 0.015), sleep terror (29% versus 9%, p < 0.0005), injured yourself during sleep (15% versus 4%, p < 0.0005), and nightmare (82% versus 65%, p = 0.012) were all reported more often by subjects with depressive mood than by subjects without depressive mood. Symptoms of sleep apnea were reported by 2.9% of the respondents. ‘‘Sleep related groaning” was reported more often in these subjects than in subjects without symptoms of sleep apnea (52% versus 31%, p = 0.016). No other significant associations between symptoms of sleep apnea and parasomnias were found. Symptoms of insomnia were reported by 24.7%. Confusional arousal (23% versus 17%, p = 0.034) and sleep terror (15% versus Table 3 The number of parasomnias (based on lifetime prevalence) each subject reported. Percentage of subjects (%) No parasomnia One parasomnia Two parasomnias Three parasomnias Four parasomnias Five parasomnias Six parasomnias Seven parasomnias Eight parasomnias Nine parasomnias Ten parasomnias All eleven parasomnias 9.8 19.3 26.8 19.8 12.1 7.6 2.2 1.3 0.6 0.2 0.2 0.0 (0.2–1.1) (4.7–7.7) (1.0–2.7) (0.4–1.6) (0.0–0.6) (0.0–0.9) (1.8–3.9) (-0.1–0.5) (3.0–5.5) (0.0–0.8) 9%, p = 0.003) were reported more often by these respondents than in subjects without symptoms of insomnia. Symptoms of restless legs were reported by 9.9%. Only confusional arousal was reported more often by these subjects compared to respondents without symptoms of restless legs (29% versus 17%, p = 0.004). Only 9.8% of the respondents reported no lifetime prevalence of parasomnia (Table 3). Most respondents reported one, two or three parasomnias. A total of 12.1% of the respondents reported having five or more parasomnias (Table 3). Table 4 shows the correlations between the different parasomnias. Most parasomnias were significantly correlated, but no correlation was larger than 0.22. 4. Discussion This is one of few population based studies investigating the prevalence of different parasomnias. The data suggest that several parasomnias, such as sleep walking, sleep talking, and nightmare, are highly prevalent in the general population. Not surprisingly, some respondents reported having several parasomnias [1,7]. The prevalence for most parasomnias was comparable to other studies [1,2,11,15]. However, the prevalence of injuring oneself (4.3%) or somebody else (3.8%) during sleep were higher. A study with 5000 adult subjects from United Kingdom reported violent or injurious behaviors during sleep in 2.1% [16]. In a study among psychiatric outpatients sleep violence was reported by 3.6% [9]. There were few gender differences. Similarly, other studies have reported no gender differences in sleep walking, sleep terror, and confusional arousals [2]. More females reported nightmare, similar to data from previous studies [1,17]. We found no difference between males and females concerning dream enactment, similar to other studies [11]. However, Nielsen et al. report that females Table 4 Correlations (phi coefficients) between the different parasomnias (based on lifetime prevalence). 1 1.Sleep walking 2. Sleep talking 3. Confusional arousal 4. Sleep terror 5. Injured yourself during sleep 6. Injured somebody else during sleep 7. Sexual acts during sleep 8. Nightmare 9. Dream enactment 10. Sleep related groaning 11. Sleep-related eating * ** p < 0.05. p < 0.01. 2 3 4 5 6 7 8 9 10 11 0.22** 0.20** 0.17** 0.07* 0.05 0.19** 0.05 0.11** 0.15** 0.17** 0.12** 0.06* 0.11** 0.10** 0.22** 0.10** 0.08* 0.09** 0.11** 0.14** 0.21** 0.01 0.22** 0.12** 0.13** 0.01 0.03 0.04 0.08* 0.07* 0.18** 0.06 0.17** 0.13** 0.19** 0.11** 0.09** 0.17** 0.13** 0.12** 0.10** 0.13** 0.12** 0.18** 0.14** 0.08* 0.01 0.06 0.12** 0.05 0.08** 0.15** 0.01 0.14** 0.08** 1034 B. Bjorvatn et al. / Sleep Medicine 11 (2010) 1031–1034 and males differ in their content of dream enactment: females report more speaking, crying, fear and laughing, whereas males report more sexual arousal [11]. Surprisingly, we did not find any gender difference in sleep-related eating, although most studies suggest a clear female predominance [1,18]. A cross-sectional study among psychiatric outpatients emphasizes parasomnia as an overlooked occurrence [9]. Our results showed that depressive mood was associated with increased prevalence of confusional arousal, sleep terror, self-inflicted injury during sleep, and nightmare. These findings are in line with increased risk for sleep walking, sleep-related injury, sleep-related eating disorder, and REM sleep behavior-like disorders in mental disorders [2,9]. The consequences of these conditions could be serious. However, the etiology of parasomnia in depression and other psychiatric disorders is complex. Mental illness, sleep disturbance, and use of psychotropic drugs may all contribute to precipitating the parasomnia [9]. In previous studies parasomnias have been reported in close association with other sleep disorders, with sleep apnea being a prominent example [1,3,8]. But in our population based study, only sleep related groaning (snoring not included) was reported more often in subjects with symptoms of sleep apnea than in subjects without such symptoms. This may indicate that the relationship differs in clinical samples compared to community based samples. Similar to sleep apnea, respondents with symptoms of insomnia and restless legs did not report most parasomnias more often than respondents without these symptoms. The exceptions were confusional arousal, where symptoms of both insomnia and restless legs were associated with an increased prevalence, and sleep terror where symptoms of insomnia were associated with an increased prevalence. In contrast to our study, a strong association between restless legs and sleep-related eating disorder was recently reported [19]. Some limitations of the present study should be noted. The response rate of 25.4% was low, and this warrants caution in the interpretation of the data. The response rate was lower than in a comparable epidemiological study performed some years earlier [20]. According to the opinion-research institute low response rates are increasingly becoming a problem with telephone interviews, likely due to the multitude of such surveys being conducted. In most of these surveys, the potential respondents accept or reject participation before being asked specific questions. Thus, it is unlikely that the respondents had any personal interests involved, and this reduces any possible selection bias. Another important limitation with our study is the use of single and relatively nonspecific questions asked by non-medical personnel. The respondents may have had problems with the interpretation of some of the questions. In order to diagnose a parasomnia in clinical settings, several questions are usually needed and the questions are normally asked by a trained clinician. The results from our study are limited to the main symptoms of each parasomnia and therefore need to be interpreted with caution. Interestingly, Nielsen et al. report higher prevalence of certain parasomnias when more detailed and specific questions were asked compared to when the questions were nonspecific and comprised simple wording [11]. This may indicate that our results represent an underestimation of true prevalence. It is also known that refusal to participate in surveys is associated with different kinds of pathology [21], further strengthening the assumption that our results may be underestimates of the real prevalence. Another limitation of the current study is that lifetime prevalence is subject to recall bias, since the parasomnia may have occurred several years before the telephone interview. The prevalence of possible sleep apnea, insomnia, restless legs, and depression were in line with previous studies [1], suggesting that the subjects were representative of the general population. 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