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At least 19 recordsLinked to original sources
PubMed2025

Familial and sporadic non-rapid eye movement parasomnia in adults: clinical and sleep differences.

STUDY OBJECTIVES: The heritable trait of non-rapid eye movement (NREM) parasomnias is well known, but differences between sporadic and familial phenotypes have not been studied. The aim of our study was to evaluate, in a clinical series of adults with NREM parasomnias, clinical and sleep differences between familial versus sporadic forms, and between childhood versus adolescent versus adult-onset forms. METHODS: We prospectively collected clinical features, family history, questionnaires (Epworth Sleepiness Score and Paris Arousal Disorders Severity Scale (PADSS)), and video-polysomnography measures from patients with NREM parasomnias confirmed by video-polysomnography, admitted over a 12-year period. Familial NREM parasomnia was defined as having at least one relative of the index case with NREM parasomnia. RESULTS: Of the 625 consecutive adults with NREM parasomnias, 50% had a family history of NREM parasomnia (most commonly parents, followed by siblings, then children). Compared to those with sporadic NREM parasomnias, participants with familial NREM parasomnias had an earlier age of onset and greater severity of NREM parasomnias (according to the PADSS). They were more likely to report sleepwalking, sleep terrors, and a combination of parasomniac manifestations (but no more confusional arousals or sleep-related eating disorders), and were less likely to report sexsomnia. In contrast, monthly episode frequency, sleepiness score, sleep structure, and EEG and behavioral markers of NREM parasomnias did not differ between groups. CONCLUSIONS: Familial NREM parasomnias have a typical phenotype with an earlier age of onset and a more severe clinical course. This phenotyping may guide medical care and future genetic studies.

Humans↗
PubMed2004

The prevalence of parasomnias in preadolescent school-aged children: a Turkish sample.

STUDY OBJECTIVES: To survey the prevalence of parasomnias in a population of children aged 7 to 11 years and to determine whether parasomnias are associated with medical and neurobehavioral properties. DESIGN: Parents and children completed a pediatric sleep questionnaire that contains 27 items developed by the authors to assess parasomnias in children. Parents and children were also interviewed about the children's medical and sociofamilial history, schooling, psychological difficulties, medication intake, and the history of psychomotor and psychosocial development. SETTING: NA PARTICIPANTS: 971 preadolescent school-aged children from 4 locations in Turkey participated in the study. RESULTS: We found a 14.4% prevalence of parasomnia in preadolescent school-aged children. Almost every sixth child had about at least 1 parasomnia. When we examined parasomnias separately, bruxism, nocturnal enuresis, and night terrors were the most common parasomnias among both girls and boys. The prevalence of parasomnias was higher in the 9- and 10-year-old age groups than in the other age groups. Girls and boys did not differ. Children with parasomnias had higher rates of past physical illness, delays in toilet raining, behavior disturbances, adjustment problems, and learning difficulties. CONCLUSIONS: These results suggest that the prevalence of parasomnias was high in the 9- and 10-year-old age groups. Parasomnias are associated with a history of physical illness and neurobehavioral abnormalities.

Child↗
PubMed2005

The primary parasomnias. A review for neurologists.

BACKGROUND: Primary parasomnias are undesirable motor or verbal phenomena which occur during sleep and result in abnormal arousals. They occur out of all sleep stages or during transitions between sleep and awake. Secondary parasomnias are sleep disturbances that are caused by disorders of other organ systems. This review addresses only primary parasomnias. Arousal disorders and the parasomnias associated with REM sleep are the primary parasomnias most likely to be seen in a neurology practice. Sleep-wake transition disorders are also discussed with nocturnal leg cramps, probably the most common in this group. REVIEW SUMMARY: The salient clinical features of the primary parasomnias are discussed. Emphasis is placed on the differential diagnosis of the different conditions and the best management strategies. Parasomnias encountered in infancy, such as infant sleep apnea, are not discussed in this review. CONCLUSIONS: Parasomnias are common disturbances of sleep that may significantly affect the patient's quality of life and that of the bed partner. Most parasomnias can be diagnosed with careful history taking and polysomnography, and management is usually safe and effective.

Humans↗
PubMed2004

Parasomnias and sleep disordered breathing in Caucasian and Hispanic children - the Tucson children's assessment of sleep apnea study.

BACKGROUND: Recent studies in children have demonstrated that frequent occurrence of parasomnias is related to increased sleep disruption, mental disorders, physical harm, sleep disordered breathing, and parental duress. Although there have been several cross-sectional and clinical studies of parasomnias in children, there have been no large, population-based studies using full polysomnography to examine the association between parasomnias and sleep disordered breathing. The Tucson Children's Assessment of Sleep Apnea study is a community-based cohort study designed to investigate the prevalence and correlates of objectively measured sleep disordered breathing (SDB) in pre-adolescent children six to 11 years of age. This paper characterizes the relationships between parasomnias and SDB with its associated symptoms in these children. METHODS: Parents completed questionnaires pertaining to their child's sleep habits. Children had various physiological measurements completed and then were connected to the Compumedics PS-2 sleep recording system for full, unattended polysomnography in the home. A total of 480 unattended home polysomnograms were completed on a sample that was 50% female, 42.3% Hispanic, and 52.9% between the ages of six and eight years. RESULTS: Children with a Respiratory Disturbance Index of one or greater were more likely to have sleep walking (7.0% versus 2.5%, p < 0.02), sleep talking (18.3% versus 9.0%, p < 0.006), and enuresis (11.3% versus 6.3%, p < 0.08) than children with an Respiratory Disturbance Index of less than one. A higher prevalence of other sleep disturbances as well as learning problems was observed in children with parasomnia. Those with parasomnias associated with arousal were observed to have increased number of stage shifts. Small alterations in sleep architecture were found in those with enuresis. CONCLUSIONS: In this population-based cohort study, pre-adolescent school-aged children with SDB experienced more parasomnias than those without SDB. Parasomnias were associated with a higher prevalence of other sleep disturbances and learning problems. Clinical evaluation of children with parasomnias should include consideration of SDB.

Arizona↗
PubMed2005

Interobserver reliability of ICSD-R minimal diagnostic criteria for the parasomnias.

OBJECTIVE: To estimate the interobserver reliability (IR) of the minimal diagnostic criteria for the parasomnias provided in the International Classification of Sleep Disorders Revised (ICSD-R). METHODS: Fifty consecutive subjects underwent a structured interview by three doctors based on the ICSD-R minimal criteria for the diagnosis of 13 parasomnias at any time in life. IR was calculated by Kappa statistics and interpreted according to conventional categories. RESULTS: In the group of Arousal Disorders, IR was "substantial" (kappa 0.74) for confusional arousals, "slight" (kappa 0.36) for sleepwalking, "fair" (kappa -0.02) for sleep terrors. In the group of Wake-Sleep Transition Disorders, IR was "substantial" to "almost perfect", but "moderate" for sleep starts (kappa 0.41). In the group of Parasomnias usually associated with REM Sleep, IR was "substantial" (kappa 0.69) for sleep paralysis, "moderate" (kappa 0.46) for RBD, "fair" (kappa 0.25) for nightmares. In the group of Other Parasomnias, IR was "substantial" to "almost perfect" (kappa between 0.73 and 0.93). CONCLUSIONS: When the clinical diagnosis of parasomnias is based on the ICSD-R: 1) the majority of Arousal Disorders and REM sleep parasomnias showed only a "fair" to "moderate" IR; 2) all of the other parasomnias showed a "substantial" to "almost perfect" IR. Nosological entities with unsatisfactory IR share complex motor phenomenology associated with a mental state difficult for the patient to define. The source of disagreement probably lies in the difficulty in interpreting patients' reports. For these parasomnias IR must be verified and possibly improved with training.

Adolescent↗
PubMed2004

Parasomnias.

Parasomnias are defined as unpleasant or undesirable behavioral or experiential phenomena that occur predominately or exclusively during the sleep period. Initially thought to represent a unitary phenomenon, often attributed to psychiatric disease, it is now clear that parasomnias are not a unitary phenomenon but rather are the manifestation of a wide variety of completely different conditions, most of which are diagnosable and treatable. The parasomnias may be conveniently categorized as "primary sleep parasomnias" (disorders of the sleep states per se) and "secondary sleep parasomnias" (disorders of other organ systems, which manifest themselves during sleep). The primary sleep parasomnias can be classified according to the sleep state of origin: rapid eye movement (REM) sleep, non-REM (NREM) sleep, or miscellaneous (i.e., those not respecting sleep state). The secondary sleep parasomnias can be further classified by the organ system involved. The underlying pathophysiology of many parasomnias is state dissociation-the brain is partially awake and partially asleep. The result of this mixed state of being is that the brain is awake enough to perform very complex and often protracted motor and/or verbal behaviors but asleep enough not to have conscious awareness of, or responsibility for, these behaviors.

Humans↗
PubMed2000

Development of parasomnias from childhood to early adolescence.

OBJECTIVES: This study examines the prevalence and developmental changes of parasomnias and assesses gender differences, relationships between parasomnias, and associations with anxiety and family adversity using data collected during the course of a longitudinal study of a representative sample of children from Québec. METHOD: The present analyses are based on results available for 664 boys and 689 girls for whom mothers have completed questions concerning demographics, parasomnias, and anxiety level. For the prevalence and developmental aspects of parasomnias, prospective data were collected at annual intervals from 11 to 13 years old and retrospective data for the period between ages 3 and 10 years were collected when the children were 10 years old. RESULTS: Somniloquy, leg restlessness, and sleep bruxism are the most frequent parasomnias. More girls were afflicted with leg restlessness, while enuresis and somniloquy were more common in boys. High anxiety scores were found in children suffering from night terrors, somniloquy, leg restlessness, sleep bruxism, and body rocking. Parasomnias were unrelated to the index of family adversity. CONCLUSIONS: Although sleepwalking, night terrors, enuresis, and body rocking dramatically decreased during childhood, somniloquy, leg restlessness, and sleep bruxism were still highly prevalent at age 13 years, paralleling results found in adults. Sleepwalking, night terrors, and somniloquy are conditions often found together. The only robust gender difference was for enuresis. High anxiety scores in parasomnias are reported for the first time in a large, controlled study. Sociodemographic variables do not seem to play a major role in the occurrence of parasomnias.

Adolescent↗
PubMed1997

A parasomnia overlap disorder involving sleepwalking, sleep terrors, and REM sleep behavior disorder in 33 polysomnographically confirmed cases.

A series of 33 patients with combined (injurious) sleepwalking, sleep terrors, and rapid eye movement (REM) sleep behavior disorder (viz. "parasomnia overlap disorder") was gathered over an 8-year period. Patients underwent clinical and polysomnographic evaluations. Mean age was 34 +/- 14 (SD) years; mean age of parasomnia onset was 15 +/- 16 years (range 1-66); 70% (n = 23) were males. An idiopathic subgroup (n = 22) had a significantly earlier mean age of parasomnia onset (9 +/- 7 years) than a symptomatic subgroup (n = 11) (27 +/- 23 years, p = 0.002), whose parasomnia began with either of the following: neurologic disorders, n = 6 [congenital Mobius syndrome, narcolepsy, multiple sclerosis, brain tumor (and treatment), brain trauma, indeterminate disorder (exaggerated startle response/atypical cataplexy)]; nocturnal paroxysmal atrial fibrillation, n = 1; posttraumatic stress disorder/major depression, n = 1; chronic ethanol/amphetamine abuse and withdrawal, n = 1; or mixed disorders (schizophrenia, brain trauma, substance abuse), n = 2. The rate of DSM-III-R (Diagnostic and Statistical Manual, 3rd edition, revised) Axis 1 psychiatric disorders was not elevated; group scores on various psychometric tests were not elevated. Forty-five percent (n = 15) had previously received psychologic or psychiatric therapy for their parasomnia, without benefit. Treatment outcome was available for n = 20 patients; 90% (n = 18) had substantial parasomnia control with bedtime clonazepam (n = 13), alprazolam and/or carbamazepine (n = 4), or self-hypnosis (n = 1). Thus, "parasomnia overlap disorder" is a treatable condition that emerges in various clinical settings and can be understood within the context of current knowledge on parasomnias and motor control/dyscontrol during sleep.

Adult↗
PubMed2002

Parasomnias: epidemiology and management.

The category of common sleep disorders known as parasomnias includes disorders of arousal, rapid eye movement (REM) sleep behaviour disorder (RBD), nocturnal seizures, rhythmic movement disorder, and tooth grinding or 'bruxism'. Parasomnias are all characterised as undesirable physical or behavioural phenomena occurring during the sleep period. Although these conditions can be distressing and, in some cases, hazardous to the sleeper and his or her bed partner, it is important to recognise that parasomnias are diagnosable and treatable in the vast majority of patients. Evaluation begins with a careful clinical interview with the sleeper and a family member to elucidate the frequency, duration, description and timing after sleep onset of these behavioural events. Disorders of arousal are the most common type of parasomnia and cover a spectrum from calm sleepwalking to emotionally agitated or complex behaviours, such as dressing or driving, for which the patient usually has no memory upon awaking. 'Sleep terrors' are quite common in young children and are often outgrown. Disorders of arousal represent a partial, as opposed to a full, awakening from deep non-REM sleep, typically occurring within the first 60 to 90 minutes after sleep onset. RBD is characterised clinically by a history of dream-enacting behaviour, and the patient may recall dream content. REM sleep periods typically occur in the latter half of the night. Physiologically, RBD results from a lack of the normal muscle atonia that is associated with REM sleep. RBD has been linked to a number of other neurological conditions; thus, a careful review of systems and a physical examination are crucial. A formal laboratory sleep study or polysomnogram with an expanded electroencephalographic montage can help distinguish among non-REM and REM parasomnias and nocturnal seizures. The latter may manifest clinically as arousals from sleep associated with vocalisation and/or complex behaviours. Rhythmic movement disorder can include head banging or body rocking at sleep onset or during the night. Tooth grinding is a common sleep-related behaviour that, when severe, can result in dental injury. Hypnagogic hallucinations (experience of dream imagery at sleep onset) and sleep-onset paralysis (experience of muscle/body paralysis as one is falling asleep) are symptoms rather than diagnostic categories. These phenomena classically occur in many individuals with narcolepsy, but also may occur in healthy sleep-deprived individuals. Safety precautions and good general sleep hygiene measures are recommended for individuals with a parasomnia, as the disorder can be exacerbated by sleep deprivation and various other factors. When the events are frequent or particularly dramatic, medication with a long- or medium-acting benzodiazepine, such as clonazepam, at bedtime is effective therapy in most cases of non-REM disorders of arousal and RBD. A dental guard may be helpful in tooth grinders. Relaxation training and guided imagery may be helpful strategies for some patients, especially those with disorders of arousal or rhythm movement disorders. There is no evidence of any association between parasomnias and psychiatric illness. Demystification of these conditions and reassurance, particularly for parents of paediatric patients, is an important aspect of clinical intervention.

Age Factors↗
PubMed1991

Injurious sleep behavior disorders (parasomnias) affecting patients on intensive care units.

There are no previous reports on parasomnias (sleep behavior disorders) affecting patients on intensive care units (ICUs). During 8 years of clinical practice, we evaluated over 200 adults with complaints of injurious, sleep-related behaviors, 20 of whom had ICU admissions while their parasomnias had been active and generally undiagnosed/untreated. Mean age during ICU confinement was 62.8 (+/- SD 13.1) years; 85.0% (17/20) were males. Patients underwent comprehensive clinical examinations along with extensive polysomnographic and audiovisual monitoring (electrooculogram, 9 channel EEG with paper speeds of 15 and 30 mm/sec, electromyogram [submental and 4 limbs], EKG, airflow). The polysomnographic studies were diagnostic for the REM sleep behavior disorder (vigorous dream-enactment during rapid eye movement [REM] sleep) in 85.0% (17/20) of patients, and for night terrors/sleepwalking in 15.0% (3/20). Three groups of parasomnia-ICU relationships were identified: i) Parasomnias originating in ICUs, stroke-induced (n = 3); ii) Admission to ICUs resulting from parasomnia-induced injuries: C2 odontoid process fracture and C3 spinous process fracture with severe concussion (n = 2); iii) Parasomnias in patients admitted to ICUs for various other medical problems (n = 15). Physicians should be thus alerted about the possibility of injurious, but usually treatable, parasomnias in ICU patients.

Adult↗
PubMed2000

The clinical presentation of childhood partial arousal parasomnias.

Objectives: The goal of the current study was to compare the sleep characteristics of children diagnosed with a partial arousal parasomnia to a community sample and further, to compare children diagnosed with sleep terrors to those diagnosed with sleepwalking.Background: Many children experience frightened awakenings, with up to 15% meeting criteria for a parasomnia. Despite this, very little empirical data exists examining parasomnias in childhood.Method: The parents of children (between 2 and 12 years of age) referred to a pediatric sleep disorders clinic completed the Children's Sleep Habits Questionnaire (CSH) on their child. The group meeting criteria for partial parasomnia was then matched with a community sample to identify differences in sleep characteristics between children with parasomnias and a normative sample.Results: Children with parasomnias had higher rates of bedtime resistance, sleep onset delay, night waking, and reduced sleep duration than a matched community sample. Sleepwalkers had more sleep onset problems than children with sleep terrors. Almost one quarter of sleepwalkers between 3 and 12 years of age reported nocturnal enuresis.Conclusions: Children with partial arousal parasomnias do have slightly more disturbed sleep than community controls.

Journal Article↗
PubMed2002

Parasomnias decline during pregnancy.

OBJECTIVES: A survey of the effects of pregnancy on parasomnias. MATERIAL AND METHODS: In an area of a central hospital and the maternity care units in the nearby rural community, women were interviewed during and after their pregnancy with a series of five questionnaires to assess the frequency of their parasomnias. The first questionnaire covered the 3 months before becoming pregnant, the next three the trimesters of pregnancy and the last one the 3 months after delivery. Altogether 325 mothers filled all the five questionnaires and constitute the study group. RESULTS: The total number of parasomnias declined (P < 0.001) during pregnancy and even more among the primiparas than among the multiparas (difference until third trimester, P=0.02). Among various parasomnias reported, sleep talking and sleepwalking decreased from the prepregnant period to the second trimester (22.8 vs 12.6%, change P=0.003), and the reported sleep starts also diminished from the prepregnant time to the first trimester (78.5 vs 63.1%, P < 0.001), but these phenomena did not change further during the follow-up. Altogether 55.7% of the women reported having nightmares 3 months before the pregnancy, and 47.7, 49.5, 41.2 and 40.3% (change from the prepregnant period, P < 0.001), respectively, at first, second and third trimester and after the delivery. Reported hypnagogic hallucinations decreased from the prepregnant time to the first trimester (9.8 vs 6.5%, P=0.027), but returned thereafter to the previous level. During the prepregnant period, 25.8% of the women reported bruxism and only 19.9% during the first trimester (P=0.009). Though the prevalence of sleep paralysis decreased during the first trimester of pregnancy, it was the only parasomnia that increased during later pregnancy (from 5.7 to 13.3% in the second trimester, P < 0.013). CONCLUSIONS: The reported frequency of most parasomnias decreases during pregnancy and even more in primiparas than multiparas.

Adolescent↗
PubMed2004

Hypersynchronous delta sleep EEG activity and sudden arousals from slow-wave sleep in adults without a history of parasomnias: clinical and forensic implications.

STUDY OBJECTIVES: To determine the frequency of classical markers of non-rapid eye movement (NREM) parasomnias--hypersynchronous delta sleep (HSD) electroencephalogram waves and sudden arousals from slow-wave sleep (SWS)--in patients without histories of somnambulism or other NREM parasomnias. DESIGN: Retrospective review. SETTING: Sleep disorders center laboratory. PATIENTS: 82 consecutive patients without a history of parasomnias who underwent diagnostic polysomnograms; 57 men and 25 women, mean age 48+/-13.3 years, were included without regard to diagnosis or findings. All patients had at least 30 seconds of stage 3 or 4 sleep during the polysomnogram. MEASUREMENTS AND RESULTS: The primary diagnosis of all but 4 patients was obstructive sleep apnea (mean respiratory disturbance index, 30 +/- 23.6 [range, 2.7-117] per hour of sleep). Polysomnograms were then reviewed for the presence of HSD and SWS arousals. A total of 235 arousals (mean, 2.9 +/- 2.7; range, 0-14) from stage 3 or 4 sleep were noted. Eight-five percent of all patients had at least 1 SWS arousal and 45% had 3 or more SWS arousals; 85.1% of all arousals from SWS were secondary to sleep-disordered breathing, and 5.9% were secondary to leg movements. At least 1 episode of HSD (mean, 1.4 +/- 1.6; range, 0-9) was noted in 65.8% of patients. CONCLUSIONS: HSD and SWS arousals were a common finding in patients without clinical histories of sleepwalking or other parasomnias but who were found to have frequent respiratory-related arousals during sleep. HSD and SWS arousals thus have a low specificity for NREM parasomnias and, without further research, are not useful for the objective confirmation of parasomnias in clinical evaluations and in the forensic evaluation of sleepwalking as a legal defense.

Arousal↗
PubMed2005

Non-rapid eye movement sleep parasomnias.

Parasomnias are unpleasant or undesirable behavioral or experiential phenomena that occur during sleep. Once believed unitary phenomena related to psychiatric disorders, it is now clear that parasomnias result from several different phenomena and usually are not related to psychiatric conditions. Parasomnias are categorized as primary (disorders of the sleep states) and secondary (disorders of other organ systems that manifest themselves during sleep). Primary sleep parasomnias can be classified according to the sleep state of origin: rapid eye movement sleep, non-rapid eye movement sleep, and miscellaneous (those not respecting sleep state). Secondary sleep parasomnias are classified by the organ system involved.

Arousal↗
PubMed2003

Genetic aspects and genetic epidemiology of parasomnias.

Parasomnias are undesirable phenomena associated with sleep. Many of them run in families, and genetic factors have been long suggested to be involved in their occurrence. This article reviews the present knowledge of the genetics of the major classical behavioral parasomnias as well as present results from genetic epidemiological studies. The level and type of evidence for genetic effects varies much from parasomnia to parasomnia. The genetic factors are best established in enuresis, with several linkages to chromosomal loci, but their functions are not so far known. Environmental causes and gene-environment interactions are most probably also of great importance in the origin of complex traits or disorders such as parasomnias.

Arousal↗
PubMed2001

Parasomnias--an update.

Primary parasomnias are a group of sleep-related clinical disorders that occur in otherwise healthy children, which may be provoked by a variety of physical, psychosocial, and environmental stimuli. In typical cases, additional investigations are not necessary, and treatment should be instituted with the aim of reducing the frequency and adverse consequences of the parasomnia. In patients with co-existing clinical disorders, parasomnias need to be distinguished from symptoms of the underlying disorder. This article provides a brief review of the recent literature regarding parasomnias, and a clinically oriented approach to the management of parasomnias in patients with co-existing clinical disorders.

Child↗
PubMed2001

Parasomnias: co-occurrence and genetics.

In clinical practice, parasomnias are often found to run in families and to co-occur. Several studies have indicated a role of genetic factors in them. In 1990, a questionnaire (response rate, 77%) sent to the Finnish Twin Cohort, a representative population sample aged 33-60 years, surveyed the frequency of five parasomnias (sleepwalking, sleeptalking, enuresis, bruxism, and nightmares) in childhood and as adults. In assessing the phenotypic covariation and shared genetic effects between the parasomnias, we used polychoric correlations and structural equation modelling. In childhood (n = 5856 individuals), co-occurrence is highest in sleeptalking with sleepwalking (R = 0.73), nightmares (R = 0.50), and bruxism (R = 0.43). As adults (n = 8567), the results are similar (R = 0.56, 0.43, and 0.39, respectively). The analyses of shared genetic effects included 815 monozygotic and 1442 dizygotic twin pairs with complete responses on four parasomnias as adults. The strongest genetic covariation was found in sleeptalking with sleepwalking, sleeptalking with bruxism, and in sleeptalking with nightmares. The estimated proportions of shared genetic effects were 50, 30, and 26%, respectively. The present results indicate that parasomnias share some common genetic background.

Adult↗
PubMed2002

Parasomnias. Things that go thump in the night.

BACKGROUND: General practitioners are well versed with patients presenting to the surgery with sleep symptoms, however, the approach to evaluating these symptoms is often haphazard. Insomnia is the commonest presenting complaint. Sleep apnoea, although readily treatable, carries with it significant morbidity and mortality. OBJECTIVE: This article aims to highlight those disorders that occur infrequently during the night but which interrupt sleep--the parasomnias. DISCUSSION: Knowledge of the spectrum of parasomnias and their symptoms usually allows a reasonably accurate clinical diagnosis and the assistance of a sleep physician or sleep laboratory is not often required. Parasomnias may be classified by the sleep phase during which they occur. Nonrapid eye movement (NREM) parasomnias are most likely to occur during the first episode of stages 3 and 4 of NREM sleep (slow wave sleep) which is approximately one hour after sleep onset. Rapid eye movement (REM) sleep density is usually greatest in the last few hours of sleep, therefore REM sleep parasomnias are most likely to occur during this time.

Dreams↗