Post-traumatic stress disorder and sleep-what a nightmare!

According to DSM IV criteria, sleep disturbances are incorporated in the definition of post-traumatic stress disorder (PTSD). These include the re-experiencing symptoms (nightmares, criteria B) and a hyperarousal state (difficulty initiating and maintaining sleep, criteria D). PTSD patients commonly complain of sleep disturbances. Moreover, insomnia, restless sleep and trauma-related dreams might be the primary complaint of some patients. However, although subjective sleep disturbances are considered characteristic of PTSD, sleep laboratory studies have provided inconsistent evidence of objective sleep disorders. A variety of sleep architectures and sleep patterns has been reported in PTSD. However, only a few studies have controlled for comorbidities. Thus, uncertainty exists to what extent the sustained complaints of sleep disturbances in chronic PTSD are specifically related to the impact of exposure to traumatic stress, or rather are a consequence of comorbid disorders. Specific changes in REM sleep suggest a pathophysiologic role of REM sleep abnormality in PTSD (e.g. anxiety dreams, increased REM density, exaggerated startle response, decreased dream recall and elevated awakening thresholds from REM sleep). However, again, studies have failed to show consistent changes in percentage of REM sleep or in REM latency. There might be a coexistence of pressure to REM along with inhibitory forces of REM that result in high variability of REM parameters across patients. Alternatively, changes in REM sleep might reflect the effect of comorbid psychiatric disorders that results in inconsistent findings between patients. The current review tries to address these issues based on recent studies carried out in this field.     

Sleep findings in young adult patients with posttraumatic stress disorder.

BACKGROUND: Laboratory sleep studies in posttraumatic stress disorder (PTSD) have not provided consistent evidence of sleep disturbance, despite apparent sleep complaints. Most of these studies have investigated middle-aged chronic PTSD subjects with a high prevalence of comorbidities such as substance dependence and/or personality disorder. METHODS: Ten young adult PTSD patients (aged 23.4 +/- 6.1 years) without comorbidities of substance dependence and/or personality disorder underwent 2-night polysomnographic recordings. These sleep measures were compared with those of normal control subjects and were correlated with PTSD symptoms. RESULTS: Posttraumatic stress disorder patients demonstrated significantly poorer sleep, reduced sleep efficiency caused by increased wake time after sleep onset, and increased awakening from rapid eye movement (REM) sleep (REM interruption). We found significant positive correlations between the severity of trauma-related nightmare complaints and the percentage of REM interruption, as well as wake time after sleep onset. CONCLUSIONS: The results indicate that trauma-related nightmares are an important factor resulting in increased REM interruptions and wake time after sleep onset in PTSD.     

Polysomnography in patients with post‐traumatic stress disorder

Aims: The purpose of the present study was to investigate sleep structure in post‐traumatic stress disorder (PTSD) patients with and without any psychiatric comorbidities. The relationship between sleep variables and measurements of clinical symptom severity were also investigated. Methods: Sleep patterns of 24 non‐medicated male PTSD patients and 16 age‐ and sex‐matched normal controls were investigated on polysomnography on two consecutive nights. Six PTSD‐only patients and 15 PTSD patients with major depressive disorder (MDD) were also compared to normal controls. Sleep variables were correlated with PTSD symptoms. Results: Compared to the normal controls, the PTSD patients with MDD had difficulty initiating sleep, poor sleep efficiency, decreased total sleep time, decreased slow wave sleep (SWS), and a reduced rapid eye movement (REM) sleep latency. The PTSD patients without any comorbid psychiatric disorders had moderately significant disturbances of sleep continuity, and decreased SWS, but no abnormalities of REM sleep. REM sleep latency was inversely proportional to the severity of startle response. SWS was found to be inversely correlated with the severity of psychogenic amnesia. Conclusions: PTSD patients have disturbance of sleep continuity, and SWS deficit, without the impact of comorbid depression on sleep. The relationship between SWS and the inability to recall an important aspect of trauma may indicate the role of sleep in the consolidation of traumatic memories. The relationship between the severity of the startle response and REM latency may suggest that REM sleep physiology shares common substrates with the symptoms of PTSD.     

Sleep and Suicide in Psychiatric Patients

Suicidal patients often report problems with their sleep. Although sleep-related complaints and EEG (electroencephalographic) changes have been seen widely across the spectrum of psychiatric disorders, sleep complaints such as insomnia, hypersomnia, nightmares, and sleep panic attacks are more common in suicidal patients. The subjective quality of sleep as measured by self-rated questionnaires also appears to be more disturbed in suicidal depressive patients. Sleep studies have reported various polysomnographic findings including increased REM (rapid eye movement) time and REM activity in suicidal patients with depression, schizoaffective disorder, and schizophrenia. One mechanism responsible for this possible association between suicide and sleep could be the role of serotonin (5HT). Serotonergic function has been found to be low in patients who attempted and/or completed suicide, particularly those who used violent methods. Aggression dyscontrol appears to be an intervening factor between serotonin and suicide. Additionally, agents that enhance serotonergic transmission decrease suicidal behavior. Serotonin has also been documented to play an important role in onset and maintenance of slow wave sleep and in REM sleep. CSF 5-HIAA levels have been correlated with slow wave sleep in patients with depression as well as schizophrenia. Moreover, 5HT2 receptor antagonists have improved slow wave sleep. Further studies are needed to investigate the possible role of sleep disturbance in suicidal behavior.     

Sleep in a community sample of elderly war veterans with and without posttraumatic stress disorder.

BACKGROUND: Although sleep disturbances are commonly reported by individuals with posttraumatic stress disorder (PTSD), objective findings have been inconsistent, due in part to small sample sizes, comorbid psychiatric disorders, variations in the recentness of trauma exposure, and the use of PTSD subjects involved in psychiatric treatment. METHODS: A community sample of elderly males (n = 59) exposed to war trauma 28-50 years ago and free from sleep-affecting medications and disorders other than PTSD completed 3 nights of polysomnography. Of these participants, 30 met criteria for current PTSD; three were receiving supportive outpatient psychotherapy. RESULTS: Two statistically significant differences were observed: Those with PTSD had a higher percentage of rapid eye movement (REM) sleep and fewer arousals from non-REM sleep. The perceptions of sleep quality among the participants with PTSD were lower than the perceptions of non-PTSD participants. Although participants with untreated obstructive sleep apnea and sleep movement disorders were not included in the sample, many cases were detected on initial screening. Treatment resulted in improved sleep and increased feelings of well being. CONCLUSIONS: Alterations in REM and arousals characterized PTSD in this sample. When comorbid sleep disorders were ruled out, sleep was clinically similar across the groups. Trauma-related sleep disturbances that subjects reported as arising early in the course of the disorder appear to have declined over time.     

Sleep in post-traumatic stress disorder and panic: convergence and divergence

Disturbed sleep is a common clinical problem in anxiety disorders, particularly in patients with post-traumatic stress disorder (PTSD) and panic disorder (PD). Several studies have attempted to validate the subjective sleep complaints of these disorders using laboratory polysomnography. These attempts, typically focusing on PTSD or PD independently, have demonstrated inconsistent results. To our knowledge, no such studies have attempted to directly compare and contrast sleep disturbances in PTSD and PD together. Our review of the studies of subjective sleep disturbances, sleep architecture, and sleep-related biologic phenomena suggests that a comparative characterization of sleep disturbances in these two disorders is timely. Such an inference is based on our identification of several areas of convergence and divergence between PTSD and PD found in the published literature, as well as our own preliminary investigations. Specifically, PTSD and PD seem to converge on several sleep-related parameters, namely, sleep quality, presence of episodic parasomnias, and movement time. They also appear to diverge in other important sleep-related areas such as respiratory disturbances and the particular phenomenological nature of episodic parasomnias, namely nightmares or nocturnal panic attacks. Investigations focusing on such overlapping phenomena may provide groundwork for further elucidation of central fear systems underlying these two disorders. Additionally, such sleep studies have the potential to provide important insights into ongoing efforts to develop a cohesive conceptual framework into the patho-physiologies of these disorders.     

Increased delta power and discrepancies in objective and subjective sleep measurements in borderline personality disorder

BACKGROUND: Previous studies have shown depression-like sleep abnormalities in borderline personality disorder (BPD). However, findings in BPD are not unequivocal for REM dysregulation, as well as for a decrement of slow wave sleep and sleep continuity disturbances. Earlier findings in sleep EEG abnormalities in BPD may have been confounded by concomitant depressive symptoms. METHODS: Twenty unmedicated female BPD patients without current comorbid major depression and 20 sex- and age-matched control subjects entered the study. Conventional polysomnographic parameters and for the first time sleep EEG spectral power analysis was performed on two sleep laboratory nights. Subjective sleep parameters were collected by sleep questionnaires in order to assess the relationship between objective and subjective sleep measurements. RESULTS: BPD patients showed a tendency for shortened REM latency and significantly decreased NonREM sleep (stage 2). Spectral EEG analysis showed increased delta power in total NREM sleep as well as in REM sleep in BPD patients. Subjective ratings documented drastically impaired sleep quality in BPD patients for the two weeks before the study and during the two laboratory nights. CONCLUSION: Not-depressed BPD patients only showed tendencies for depression-like REM sleep abnormalities. Surprisingly, BPD patients displayed higher levels of delta power in the sleep EEG in NREM sleep than healthy control subjects. There was a marked discrepancy between objective and subjective sleep measurements, which indicates an altered perception of sleep in BPD. The underlying psychological and neurobiological mechanisms of these alterations are still unclear and need to be clarified in future studies including interventions on a pharmacological and cognitive-behavioral level.     

Disturbed sleep in post-traumatic stress disorder: secondary symptom or core feature?

Sleep disturbances are often viewed as a secondary symptom of post-traumatic stress disorder (PTSD), thought to resolve once PTSD has been treated. Specific screening, diagnosis and treatment of sleep disturbances is therefore not commonly conducted in trauma centres. However, recent evidence shows that this view and consequent practices are as much unhelpful as incorrect. Several sleep disorders-nightmares, insomnia, sleep apnoea and periodic limb movements-are highly prevalent in PTSD, and several studies found disturbed sleep to be a risk factor for the subsequent development of PTSD. Moreover, sleep disturbances are a frequent residual complaint after successful PTSD treatment: a finding that applies both to psychological and pharmacological treatment. In contrast, treatment focusing on sleep does alleviate both sleep disturbances and PTSD symptom severity. A growing body of evidence shows that disturbed sleep is more than a secondary symptom of PTSD-it seems to be a core feature. Sleep-focused treatment can be incorporated into any standard PTSD treatment, and PTSD research needs to start including validated sleep measurements in longitudinal epidemiologic and treatment outcome studies. Further clinical and research implications are discussed, and possible mechanisms for the role of disturbed (REM) sleep in PTSD are described.     

The neural correlates and temporal sequence of the relationship between shock exposure, disturbed sleep and impaired consolidation of fear extinction

Consolidation of extinction learning is a primary mechanism disrupted in posttraumatic stress disorder (PTSD), associated with hypoactivity of the ventromedial prefrontal cortex and hippocampus. A role for rapid eye movement (REM) sleep disturbances in this failure to consolidate extinction learning has been proposed. We performed functional magnetic resonance imaging (fMRI) with simultaneous skin conductance response (SCR) measurements in 16 healthy participants during conditioning/extinction and later recall of extinction. The visual stimuli were basic geometric forms and electrical shocks functioned as the unconditioned stimulus. Between the conditioning/extinction and recall sessions, participants received a 90-min sleep window in the sleep laboratory. This daytime sleep was polysomnographically recorded and scored by professionals blind to the study design. Only seven out of 16 participants had REM sleep; participants without REM sleep had a significantly slower decline of both SCR and neural activity of the laterodorsal tegmentum in response to electrical shocks during conditioning. At recall of fear extinction, participants with preceding REM sleep had a reduced SCR and stronger activation of the left ventromedial prefrontal cortex and bilateral lingual gyrus in response to the extinguished stimulus than participants lacking REM sleep. This study indicates that trait-like differences in shock reactivity/habituation (mediated by the brainstem) are predictive of REM sleep disruption, which in turn is associated with impaired consolidation of extinction (mediated by the ventromedial prefrontal cortex). These findings help understand the neurobiological basis and the temporal sequence of the relationship between shock exposure, disturbed sleep and impaired consolidation of extinction, as observed in PTSD.     

Gabapentin in PTSD: A Retrospective, Clinical Series of Adjunctive Therapy

Posttraumatic stress disorder (PTSD) symptoms may improve significantly with antidepressant medications, however some phenomena often remain refractory to the most commonly used treatments. Frequently, sleep disturbances, such as insomnia and nightmares, are symptoms of PTSD that are refractory to antidepressant treatment. Gabapentin, a novel anticonvulsant agent, has been of interest as a potential anxiolytic agent, but has not been evaluated in PTSD. We reviewed records of 30 consecutive patients who had been diagnosed with PTSD according to structured interviews and had received gabapentin as an adjunctive medication. For each patient, the target symptoms that led to the initiation of gabapentin treatment were identified. Using the most recent clinical data available, the change in target symptom severity following treatment was rated as unimproved, mildly improved, moderately improved, or markedly improved. The gabapentin was often first prescribed to facilitate sleep. The majority (77%) of patients showed moderate or greater improvement in duration of sleep, and most noted a decrease in the frequency of nightmares. The dose range was 300–3600 mg/day. Sedation and mild dizziness were the most commonly reported side effects. This retrospective study suggests that gabapentin may improve in particular sleep difficulties and also other symptoms associated with chronic PTSD. Prospective, controlled studies are needed to further investigate the effects of gabapentin on insomnia, nightmares, and other core PTSD symptoms.     

Interstitial lung disease and sleep: What is known?

ObjectivesPulmonary fibrosis (PF), a group of disorders characterized by progressive scarring of the lung parenchyma, affects over 500,000 Americans. Fatigue is a common and frequently disabling symptom in PF. We have previously described poor subjective sleep quality in this patient population. We sought to ascertain what is known regarding sleep in PF.MethodsWe reviewed the English language literature for reports on sleep and sleep disorders in patients with PF.ResultsThe existing literature is small and heterogeneous with regard to inclusion criteria. There are a number of distinctive changes in sleep architecture associated with PF including decreased REM sleep and increased sleep fragmentation. In addition, there is suggestion of possible sleep disturbances in this population including OSA, although the frequency of such sleep abnormalities as well as predictors of these abnormalities remain uncertain.ConclusionsThere is significant need for larger studies characterizing sleep in patients with defined PF. These studies are particularly critical given the limited options for therapy in patients with PF and the impact of fatigue in this disorder.     

Actigraphic sleep monitoring in posttraumatic stress disorder (PTSD) patients

Posttraumatic stress disorder (PTSD) patients frequently complain that they suffer from sleep disturbances. To date, the polysomnographic studies that have attempted to study PTSD patients' subjective complaints of sleep difficulties have produced conflicting results. The objective of the present study was to compare PTSD patients' subjective complaints of poor sleep and objective actigraphic recordings of their sleep over a period of several consecutive nights. The results indicate that PTSD patients do not suffer from poorer sleep than a control group, based on actigraphic measures, and that their subjective sleep evaluation is inconsistent with objective sleep measures. These patients fail to correctly estimate their sleep.     

Sleep disturbance in anxiety disorders

Many patients suffering from the majority of anxiety disorders complain about their sleep by reporting difficulties in initiating and maintaining it. Polysomnographic studies have shown that, in comparison to normal subjects, the sleep of patients with panic disorder is characterized by longer sleep latency, increased time awake and reduced sleep efficiency. Sleep architecture is normal and there are no significant changes in REM sleep measures. Nocturnal panic attacks are non-REM-related events and occur without an obvious trigger in 18-45% of panic disorder patients. Regarding generalized anxiety disorder, the patients complain of 'trouble sleeping' in 60-70%, while polysomnography has shown increased sleep latency and decreased sleep continuity measures. The findings in REM sleep and sleep architecture generally do not show any aberration to exist. In patients with obsessive-compulsive disorder (OCD) and post-traumatic stress disorder (PTSD), results from the sleep laboratory do not seem to support the subjective complaints of poor sleep. The early reports of shortened REM latency in OCD could not be replicated by recent studies. A dysregulation of the REM sleep control system has been reported for patients with PTSD. Finally, no significant differences were found in all sleep parameters between social phobia patients and controls.     

Early phenotypic differences between Parkinson's disease patients with and without freezing of gait

BackgroundPrevious studies have associated freezing of gait in Parkinson's disease with the presence of specific phenotypic features such as mood disturbances, REM sleep behavior disorder and selective cognitive impairments. However, it is not clear whether these features are present in the earlier stages of disease or simply represent a more general pattern of progression. To investigate this issue, the current study evaluated motor, cognitive, affective and autonomic features as well as REM sleep behavior disorder in Parkinson's disease patients in the early stages of the condition.MethodsThirty-eight freezers and fifty-three non-freezers with disease duration of less than five years and a Hoehn and Yahr stage of less than three were included in this study. The groups were matched on a number of key disease features including age, disease duration, motor severity and dopamine dose equivalence. Furthermore, patients were assessed on measures of motor, cognitive, affective and autonomic features, as well as REM sleep behavior disorder.ResultsCompared to non-freezers, patients with freezing of gait had significantly more non-tremor symptoms and a selective impairment on executive functions, such as set-shifting ability and working memory. Freezers and non-freezers did not differ on measures of tremor, autonomic function, REM sleep behavior disorder, mood or more general cognition.ConclusionThese results suggest the pathophysiological mechanisms underlying freezing of gait in the early clinical stages of Parkinson's disease are likely to be related to specific changes in the frontostriatal pathways rather than being due to brainstem or more diffuse neuropathology.     

Heart rate variability during sleep and the early development of posttraumatic stress disorder

Background

Noradrenergic function has been linked to posttraumatic stress disorder (PTSD) and might have a role in mediating sleep disturbances of the disorder. Our objective was to relate a peripheral manifestation of noradrenergic function, sympathetic nervous system activity as indexed by heart rate variability during sleep, to the development of PTSD in subjects with recent traumatic injuries.

Methods

Subjects who had recall of life-threatening experiences were recruited from one of two regional trauma centers. Select subjects received a polysomnographic recording within 1 month of the trauma. Digitized electrocardiogram recordings were extracted from early and late rapid-eye-movement (REM) and preceding non-REM sleep periods. Autoregression was applied to R-R interval time series to calculate the ratios of low-frequency to high-frequency spectral densities (LF/HF ratios), which index sympathetic activation. Posttraumatic stress disorder status was determined at 2 months.

Results

There was a significant state × group interaction: LF/HF ratios were higher during the REM sleep of the nine subjects who were positive for PTSD symptoms, compared with the 10 subjects who were PTSD negative.

Conclusions

Our findings are consistent with the possibility that increased noradrenergic activity during REM sleep contributes to the development of PTSD.     

Sleep in lifetime posttraumatic stress disorder: a community-based polysomnographic study

BACKGROUND: Sleep complaints are common in posttraumatic stress disorder (PTSD) and are included in the DSM criteria. Polysomnographic studies conducted on small samples of subjects with specific traumas have yielded conflicting results. We therefore evaluated polysomnographic sleep disturbances in PTSD. METHODS: A representative cohort of young-adult community residents followed-up for 10 years for exposure to trauma and PTSD was used to select a subset for sleep studies for 2 consecutive nights and the intermediate day. Subjects were selected from a large health maintenance organization and are representative of the geographic area except for the extremes of the socioeconomic status range. The subset for the sleep study was selected from the 10-year follow-up of the cohort (n = 913 [91% of the initial sample]). Eligibility criteria included (1) subjects exposed to trauma during the preceding 5 years; (2) others who met PTSD criteria; and (3) a randomly preselected subsample. Of 439 eligible subjects, 292 (66.5%) participated, including 71 with lifetime PTSD. Main outcomes included standard polysomnographic measures of sleep induction, maintenance, staging, and fragmentation; standard measures of apnea/hypopnea and periodic leg movement; and results of the multiple sleep latency test. RESULTS: On standard measures of sleep disturbance, no differences were detected between subjects with PTSD and control subjects, regardless of history of trauma or major depression in the controls. Persons with PTSD had higher rates of brief arousals from rapid eye movement (REM) sleep. Shifts to lighter sleep and wake were specific to REM and were significantly different between REM and non-REM sleep (F(1,278) = 5.92; P =.02). CONCLUSIONS: We found no objective evidence for clinically relevant sleep disturbances in PTSD. An increased number of brief arousals from REM sleep was detected in subjects with PTSD. Sleep complaints in PTSD might represent amplified perceptions of brief arousals from REM sleep.     

Sleep disturbance as the hallmark of posttraumatic stress disorder

The reexperiencing of a traumatic event in the form of repetitive dreams, memories, or flashbacks is one of the cardinal manifestations of posttraumatic stress disorder (PTSD). The dream disturbance associated with PTSD may be relatively specific for this disorder, and dysfunctional REM sleep mechanisms may be involved in the pathogenesis of the posttraumatic anxiety dream. Furthermore, the results of neurophysiological studies in animals suggest that CNS processes generating REM sleep may participate in the control of the classical startle response, which may be akin to the startle behavior commonly described in PTSD patients. Speculating that PTSD may be fundamentally a disorder of REM sleep mechanisms, the authors suggest several strategies for future research.     

Sleep pathophysiology in posttraumatic stress disorder and idiopathic nightmare sufferers.

BACKGROUND: Nightmares are common in posttraumatic stress disorder (PTSD), but they also frequently occur in idiopathic form. Findings associated with sleep disturbances in these two groups have been inconsistent, and sparse for idiopathic nightmares. The aim of the present study was to investigate whether sleep anomalies in PTSD sufferers with frequent nightmares (P-NM) differ from those observed in non-PTSD, idiopathic nightmare (I-NM) sufferers and healthy individuals. METHODS: Sleep measures were obtained from nine P-NM sufferers, 11 I-NM sufferers, and 13 healthy control subjects. All participants slept in the laboratory for two consecutive nights where electroencephalogram, electro-oculogram, chin and leg electromyogram, electrocardiogram, and respiration were recorded continuously. RESULTS: Posttraumatic nightmare sufferers had significantly more nocturnal awakenings than did I-NM sufferers and control subjects. Elevated indices of periodic leg movements (PLMs) during rapid eye movement (REM) and non-REM sleep characterized both P-NM and I-NM sufferers. CONCLUSIONS: Posttraumatic nightmare sufferers exhibit more nocturnal awakenings than do I-NM sufferers and control subjects, which supports the hypothesis of hyperarousal in sleep in PTSD sufferers; however, elevated PLM indices in both P-NM and I-NM sufferers suggest that PLMs may not be a marker of hyperarousal in sleep of PTSD sufferers. Rather, PLMs may be a correlate of processes contributing to intense negative dreaming.     

Non-REM sleep instability in patients with major depressive disorder: subjective improvement and improvement of non-REM sleep instability with treatment (Agomelatine)

OBJECTIVE: To assess the importance of non-rapid eye movement (NREM) sleep disturbance in major depressive disorder (MDD) patients using cyclic alternating pattern (CAP) analysis, and to determine the usefulness of CAP analysis in evaluating treatment effect. METHODS: Baseline sleep-staging data and CAP analysis of NREM sleep was compared in 15 MDD patients (Hamilton depression scale score>20) and normal controls. Longitudinal evaluation of sleep changes using similar analysis during a treatment trial was also performed. ANALYSIS: A single-blinded researcher scored and analyzed the sleep of MDD and age-matched normal controls at baseline and during a treatment trial using the international scoring system as well as CAP analysis. RESULTS: MDD patients had evidence of disturbed sleep with both analyses, but CAP analysis revealed more important changes in NREM sleep of MDD patients at baseline than did conventional sleep staging. There was a significant decrease in CAP rate, time, and cycle and disturbances of phase A subtype of CAP. NREM abnormalities, observed by CAP analysis, during the treatment trial paralleled subjective responses. Analysis of subtype A phase of CAP demonstrated better sleep improvement. CONCLUSION: CAP analysis demonstrated the presence of more important NREM sleep disturbances in MDD patients than did conventional sleep staging, suggesting the involvement of slow wave sleep (SWS) in the sleep impairment of MDD patients. Improvement of NREM sleep paralleled subjective mood improvement and preceded REM sleep improvement. CAP analysis allowed objective investigation of the effect of treatment on sleep disturbances.     

Sleep disorders in multiple system atrophy

Summary. Complaints about sleep disorders and excessive daytime sleepiness are common among patients with multiple system atrophy. The diffuse neurodegenerative process that encompasses the key structures involved in the regulation of the sleep/wake transition and respiratory function may account for these complaints and for the most frequent polysomnographic findings in MSA, i.e., sleep-related breathing disturbances and REM sleep behaviour disorder, which are both treatable conditions. Nocturnal stridor is an inspiratory sound produced by complex vocal cord muscle dysfunction. Often occurring with sleep apnoea, stridor is associated with decreased survival. REM sleep behaviour disorder, a parasomnia characterized by loss of normal skeletal muscle atonia during REM sleep with prominent motor activity, is detected in almost all patients. The pathophysiology of both disorders is partially elucidated but increasing evidence points to the role of basal ganglia dysfunction.