Sleep Deprivation Reveals Altered Brain Perfusion Patterns in Somnambulism

Challenges in diagnosing NREM parasomnias: Implications for future diagnostic classifications

NREM parasomnias are frequent and potentially disabling sleep disorders characterized by recurrent abnormal behaviors emerging from NREM sleep. Recently, several studies provided more detailed clinical and polysomnographic characterization of NREM parasomnia which may enhance the diagnostic process. Several revisions of the diagnostic criteria have been proposed in the classification of sleep disorders, the latest being ICSD-3-TR in 2023 with no changes on NREM parasomnias since ICSD-3 published in 2014. We performed an extensive literature review to assess the evidence on the procedure of its diagnosis. We dissected the inconsistencies and shortcomings in the ICSD-3-TR to propose a revision of the current diagnostic criteria. We highlighted the limits of several clinical criteria which should rather be supportive features than mandatory criteria. Infrared cameras with video-recordings with are promising tools to precisely characterize home episodes. Sensitive and specific polysomnographic markers of NREM parasomnias have been identified and should be considered in future revisions. We also suggest the use of diagnostic specifiers (clinical subtypes, clinical significance, levels of severity, age effect, levels of certainty) to define homogeneous subgroups of patients for therapeutic intervention and research purposes. In conclusion, we advocate for significant changes in the current diagnostic criteria of NREM parasomnias for future classification.

Alterations of sleep initiation in NREM parasomnia after sleep deprivation - A multimodal pilot study

Objectives

NREM parasomnias also known as disorders of arousal (DOA) are characterised by abnormal motor and autonomic activation during arousals primarily from slow wave sleep. Dissociative state between sleep and wake is likely responsible for clinical symptoms of DOA. We therefore investigated potential dissociation outside of parasomnic events by using simultaneous 256-channel EEG (hdEEG) and functional magnetic resonance imaging (fMRI).

Methods

Eight DOA patients (3 women, mean age = 27.8; SD = 4.2) and 8 gender and age matched healthy volunteers (3 women, mean age = 26,5; SD = 4.0) were included into the study. They underwent 30-32 h of sleep deprivation followed by hdEEG and fMRI recording. We determined 2 conditions: falling asleep (FA) and arousal (A), that occurred outside of deep sleep and/or parasomnic event. We used multimodal approach using data obtained from EEG, fMRI and EEG-fMRI integration approach.

Results

DOA patients showed increase in delta and beta activity over postcentral gyrus and cuneus during awakening period. This group expressed increased connectivity between motor cortex and cingulate during arousals unrelated to parasomnic events in the beta frequency band. They also showed lower connectivity between different portions of cingulum. In contrast, the greater connectivity was found between thalamus and some cortical areas, such as occipital cortex.

Conclusion

Our findings suggest a complex alteration in falling asleep and arousal mechanisms at both subcortical and cortical levels in response to sleep deprivation. As this alteration is present also outside of slow wave sleep and/or parasomnic episodes we believe this could be a trait factor of DOA.

Association of Sleep Disturbances With Brain Amyloid and Tau Burden, Cortical Atrophy, and Cognitive Dysfunction Across the AD Continuum

BACKGROUND AND OBJECTIVES

Patients with Alzheimer disease (AD) frequently suffer from various sleep disturbances. However, how sleep disturbance is associated with AD and its progression remains poorly investigated. We investigated the association of total sleep time with brain amyloid and tau burden, cortical atrophy, cognitive dysfunction, and their longitudinal changes in the AD spectrum.

METHODS

In this retrospective cohort study, we enrolled participants on the AD spectrum who were positive on 18F-florbetaben (FBB) PET. All participants underwent the Pittsburgh Sleep Quality Index, brain MRI, FBB PET, 18F-flortaucipir (FTP) PET, and detailed neuropsychological testing. In addition, a subset of participants completed follow-up assessments. We analyzed the association of total sleep time with the baseline and longitudinal FBB-standardized uptake value ratio (SUVR), FTP-SUVR, cortical thickness, and cognitive domain composite scores.

RESULTS

We examined 138 participants on the AD spectrum (15 with preclinical AD, 62 with prodromal AD, and 61 with AD dementia; mean age 73.4 ± 8.0 years; female 58.7%). Total sleep time was longer in the AD dementia group (7.4 ± 1.6 hours) compared with the preclinical (6.5 ± 1.4 hours; p = 0.026) and prodromal groups (6.6 ± 1.4 hours; p = 0.001), whereas other sleep parameters did not differ between groups. Longer total sleep time was not associated with amyloid accumulation but rather with tau accumulation, especially in the amygdala, hippocampus, basal forebrain, insular, cingulate, occipital, inferior temporal cortices, and precuneus. Longer total sleep time predicted faster tau accumulation in Braak regions V-VI (β = 0.016, p = 0.007) and disease progression to mild cognitive impairment or dementia (hazard ratio = 1.554, p = 0.024). Longer total sleep time was also associated with memory deficit (β = -0.19, p = 0.008).

DISCUSSION

Prolonged total sleep time was associated with tau accumulation in sleep-related cortical and subcortical areas as well as memory dysfunction. It also predicted faster disease progression with tau accumulation. Our study highlights the clinical importance of assessing total sleep time as a marker for disease severity and prognosis in the AD spectrum.

Violent and Complex Behaviors and Non-Restorative Sleep Are the Main Features of Disorders of Arousal in Adulthood: Real Picture or a More Severe Phenotype?

Disorders of arousal (DoA) are NREM parasomnias characterized by motor and emotional behaviors emerging from incomplete arousals from deep sleep. DoA are largely present in pediatric populations, a period during which they are labeled as self-limited manifestations. However, an extensive literature has shown that DoA can persist in adulthood, with different characteristics from childhood DoA. Adult DoA patients usually report excessive daily sleepiness, sleep-related violence during DoA episodes or potentially harmful behaviors, which are rare in childhood. The semeiological features of DoA episodes in adulthood may complicate differential diagnoses with other motor manifestations during sleep, in particular sleep-related hypermotor epilepsy. However, it cannot be excluded that adults with DoA attending sleep centers constitute a more severe phenotype, thus not being representative of adult DoA in the general population. Video-polysomnographic studies of DoA document a spectrum of motor patterns of different complexities, the simplest of which may often go unnoticed. Despite the different complexities of the episodes, neurophysiologic studies showed the co-existence of deep sleep and wakefulness during DoA episodes or even before their onset. These aspects make DoA an ideal model to investigate the mechanisms regulating local sleep, sleep arousal and cognitive functions including spatial and temporal orientation, attention or memory.

Sleepwalking, sleep terrors, sexsomnia and other disorders of arousal: the old and the new

Disorders of arousal (DOA) is an umbrella term initially covering classical sleepwalking, sleep terrors, and confusional arousals, and now including a wider spectrum of specialised forms of non rapid eye movement (non REM) parasomnias such as sexsomnia, sleep-related eating disorder, and sleep-related choking syndrome. Growing evidence has shown that DOA are not restricted to children but are also prevalent in adults (2%-4% of the adult population). While DOA run in family, genetics studies remain scarce and inconclusive. In addition to the risk of injury on themselves and others (including sexual assaults in sexsomnia), adults with DOA frequently suffer from excessive daytime sleepiness, pain, and altered quality of life. The widespread view of DOA as automatic and amnesiac behaviours has now been challenged by subjective (dream reports) and objective (dream-enacting behaviours documented on video-polysomnography) observations, suggesting that sleepwalkers are 'dream walking' during their episodes. Behavioural, experiential, cognitive, and brain (scalp electroencephalography [EEG], stereo-EEG, high density-EEG, functional brain imaging) data converge in showing a dissociated pattern during the episodes. This dissociated pattern resembles the new concept of local arousal with a wake-like activation in motor and limbic regions and a preserved (or even increased) sleep intensity over a frontoparietal network. EEG and behavioural criteria supporting the DOA diagnosis with high sensitivity and specificity are now available. However, treatment is still based on controlling priming and precipitating factors, as well as on clinicians' personal experience with sedative drugs. Placebo-controlled trials are needed to improve patients' treatment. DOA deserve more attention from sleep researchers and clinicians.

The gray matter volume of bilateral inferior temporal gyrus in mediating the association between psychological stress and sleep quality among Chinese college students

The role of brain regions in the relationship between psychological stress and sleep quality is unclear. This study investigates the neuroanatomical basis of the association between psychological stress and sleep quality. Data were collected using the Pittsburgh Sleep Quality Index, the Psychosomatic Tension Relaxation Inventory, and voxel-based morphometry among 318 healthy students. The results showed that psychological stress was negatively correlated with sleep quality. According to the mediation analysis results, the correlation between psychological stress and sleep quality was partially mediated by the region of the bilateral inferior temporal gyrus. These findings suggest that there is a strong link between sleep quality and psychological stress, highlighting the gray matter volume of the bilateral inferior temporal gyrus related to emotional processing, which plays an essential role in improving sleep quality.

NREM sleep parasomnias as disorders of sleep-state dissociation

Non-rapid eye movement (NREM) sleep parasomnias (or NREM parasomnias) are fascinating disorders with mysterious neurobiological substrates. These conditions are common and often severe, with social, personal and forensic implications. The NREM parasomnias include sleepwalking, sleep terrors and confusional arousals - collectively termed disorders of arousal (DOAs) - as well as less well-known entities such as sleep-related sexual behaviours and eating disorders. Affected patients can exhibit waking behaviours arising abruptly out of NREM sleep. Although the individual remains largely unresponsive to the external environment, their EEG shows both typical sleep-like and wake-like features, and they occasionally report dreaming afterwards. Therefore, these disorders offer a unique natural model to explore the abnormal coexistence of local sleep and wake brain activity and the dissociation between behaviour and various aspects of consciousness. In this article, we critically review major findings and updates on DOAs, focusing on neurophysiological studies, and offer an overview of new clinical frontiers and promising future research areas. We advocate a joint effort to inform clinicians and the general public about the management and follow-up of these conditions. We also strongly encourage collaborative multicentre studies to add more objective polysomnographic criteria to the current official diagnostic definitions and to develop clinical practice guidelines, multidisciplinary research approaches and evidence-based medical care.

Non-REM Parasomnia: The Promise of Precision Medicine

Our understanding of non-REM parasomnias is just beginning to unfold the potential biomarkers and underlying pathophysiologic processes that lead to these events. Biomarkers need further investigation and will help us to understand better ways to develop risk models and possible mechanisms. Similarly, as we develop more accurate pathophysiologic-based diagnostic testing for non-REM parasomnias, we will begin the evolution toward a physiologic-based classification scheme that aids the application of precision medicine. This article explores currently known characteristics and exploratory features that may aid in this transition to better understanding our individual patients with non-REM parasomnias and tailoring their treatments.

Altered brain perfusion patterns in wakefulness and slow-wave sleep in sleepwalkers

Study Objectives

The present study assessed brain perfusion patterns with single-photon emission computed tomography (SPECT) during sleepwalkers' post-sleep deprivation slow-wave sleep (SWS) and resting-state wakefulness.

Methods

Following a 24 hr period of sleep deprivation, 10 sleepwalkers and 10 sex- and age-matched controls were scanned with a high-resolution SPECT scanner. Participants were injected with 99mTc-ethylene cysteinate dimer after 2 min of stable SWS within their first sleep cycle as well as during resting-state wakefulness, both after a subsequent 24 hr period of sleep deprivation.

Results

When compared with controls' brain perfusion patterns during both SWS and resting-state wakefulness, sleepwalkers showed reduced regional cerebral perfusion in several bilateral frontal regions, including the superior frontal, middle frontal, and medial frontal gyri. Moreover, reduced regional cerebral perfusion was also found in sleepwalkers' left postcentral gyrus, insula, and superior temporal gyrus during SWS compared with controls. During resting-state wakefulness compared with controls, reduced cerebral perfusion was also found in parietal and temporal regions of sleepwalkers' left hemisphere, whereas the right parahippocampal gyrus showed increased regional cerebral perfusion.

Conclusions

Our results reveal patterns of reduced regional cerebral perfusion in sleepwalkers' frontal and parietal areas when compared with controls, regions previously associated with SWS generation and episode occurrence. Additionally, reduced perfusion in the dorsolateral prefrontal cortex and insula during recovery SWS is consistent with the clinical features of somnambulistic episodes, including impaired awareness and reduced pain perception. Altered regional cerebral perfusion patterns during sleepwalkers' resting-state wakefulness may be related to daytime functional anomalies in this population.

Regional cerebral hypoperfusion after acute sleep deprivation: A STROBE-compliant study of arterial spin labeling fMRI

Previous neuroimaging studies have shown that functional changes occur after acute sleep deprivation, which suggest detrimental effects of a lack of sleep on the intrinsic functional architecture of the brain. We aimed to identify regional resting perfusion changes in subjects with acute sleep deprivation.Thirty-three healthy subjects with habitual good sleep participated in 36 hours (2 days and 1 night) of sleep deprivation and then underwent the attention network test and pseudo-continuous arterial spin labeling scanning. Regional cerebral blood flow was used to compare cerebral perfusion before and after sleep deprivation. Correlation analyses of regional perfusion changes and scores on the attention network test were performed.Compared with the baseline (n = 20) scans, the scans of subjects after sleep deprivation (n = 26) revealed a slower response time (549.99 milliseconds vs 603.36 milliseconds; t = -2.301; P = .028) and a significantly higher lapse rate (0.88% vs 22.85%; t = -2.977; P = .006). The sleep deprivation subjects showed lower cerebral blood flow (CBF) in the left parahippocampal gyrus/fusiform cortex (pHipp/Fus), right pHipp/Fus, and right prefrontal cortex (PFC) relative to the baseline subjects (Gaussian random field correction, voxel level P < .01, and cluster level P < .05). Although no significant relationships were observed between the altered regional CBF (rCBF) values and the attention network test scores, the receiver-operating characteristic and leave-one-out cross-validation analyses revealed that significant decreases in rCBF in the bilateral pHipp/Fus and right PFC could discriminate between sleep deprivation and good sleep status.We observed that rCBF was reduced after 36 hours (2 days and 1 night) of sleep deprivation. Our preliminary findings suggest an acute vulnerability to hypoperfusion due to lack of sleep.

Adult NREM Parasomnias: An Update

Our understanding of non-rapid eye movement (NREM) parasomnias has improved considerably over the last two decades, with research that characterises and explores the causes of these disorders. However, our understanding is far from complete. The aim of this paper is to provide an updated review focusing on adult NREM parasomnias and highlighting new areas in NREM parasomnia research from the recent literature. We outline the prevalence, clinical characteristics, role of onset, pathophysiology, role of predisposing, priming and precipitating factors, diagnostic criteria, treatment options and medico-legal implications of adult NREM parasomnias.

Altered Regional Cerebral Blood Flow in Idiopathic Hypersomnia

Study Objectives

Idiopathic hypersomnia is characterized by excessive daytime sleepiness, despite normal or long sleep time. Its pathophysiological mechanisms remain unclear. This pilot study aims at characterizing the neural correlates of idiopathic hypersomnia using single photon emission computed tomography.

Methods

Thirteen participants with idiopathic hypersomnia and 16 healthy controls were scanned during resting wakefulness using a high-resolution single photon emission computed tomography scanner with 99mTc-ethyl cysteinate dimer to assess cerebral blood flow. The main analysis compared regional cerebral blood flow distribution between the two groups. Exploratory correlations between regional cerebral blood flow and clinical characteristics evaluated the functional correlates of those brain perfusion patterns. Significance was set at p < .05 after correction for multiple comparisons.

Results

Participants with idiopathic hypersomnia showed regional cerebral blood flow decreases in medial prefrontal cortex and posterior cingulate cortex and putamen, as well as increases in amygdala and temporo-occipital cortices. Lower regional cerebral blood flow in the medial prefrontal cortex was associated with higher daytime sleepiness.

Conclusions

These preliminary findings suggest that idiopathic hypersomnia is characterized by functional alterations in brain areas involved in the modulation of vigilance states, which may contribute to the daytime symptoms of this condition. The distribution of regional cerebral blood flow changes was reminiscent of the patterns associated with normal non-rapid-eye-movement sleep, suggesting the possible presence of incomplete sleep-wake transitions. These abnormalities were strikingly distinct from those induced by acute sleep deprivation, suggesting that the patterns seen here might reflect a trait associated with idiopathic hypersomnia rather than a non-specific state of sleepiness.

Non-Rapid Eye Movement Arousal Parasomnias in Children

Parasomnia is a common pediatric sleep disorder that can cause parents or caregivers distress when experienced by their children. Based on the International Classification of Sleep Disorders, parasomnias can be divided into two subgroups: non-rapid eye movement (NREM) parasomnias and rapid eye movement (REM) parasomnias. REM sleep parasomnias include nightmares, REM behavior disorder, and sleep paralysis, whereas NREM sleep parasomnias include disorders of arousal such as confusional arousals, sleepwalking, sleep talking, night terrors, and sleep-related eating disorder. This review focuses on the epidemiology, clinical presentation, diagnosis, and treatment of the most common form of parasomnias-NREM arousal parasomnias. Additionally, this review aims to help clinicians distinguish NREM parasomnias from nocturnal frontal lobe seizures, as this distinction is important to avoid diagnostic delays and inappropriate medication exposure. [Pediatr Ann. 2017;46(9):e327-e331.].

Insomnia, parasomnias, and narcolepsy in children: clinical features, diagnosis, and management

Sleep problems are frequently encountered as presenting complaints in child neurology clinical practice. They can affect the functioning and quality of life of children, particularly those with primary neurological and neurodevelopmental disorders, since coexisting sleep problems can add substantially to neurocognitive and behavioural comorbidities. Additionally, symptoms of some sleep disorders such as parasomnias and narcolepsy can be confused with those of other neurological disorders (eg, epilepsy), posing diagnostic challenges for paediatric neurologists. The understanding of the neurophysiology of sleep disorders such as insomnia, parasomnias, and narcolepsy is still evolving. There is a complex relation between the sleeping brain and its waking function. The interplay among genetic factors, alterations in neurotransmitters, electrophysiological changes, and environmental factors potentially contribute to the genesis of these sleep disorders.

A biopsychosocial model of violence when sleepwalking: review and reconceptualisation

SUMMARY

Violence towards others during sleepwalking is relatively uncommon, but can result in serious injury or even death. Much of the research in this field has focused on the forensic consequences of violence during sleepwalking without sufficient attention to an understanding of the risk factors for violence during sleepwalking and the development of prevention and interventions based on these risk factors. This paper reviews the characteristics of impulsive violence in general and reconceptualises violence during sleepwalking as an extension of this prior vulnerability. We propose a biopsychosocial model of the risk for violence during sleepwalking that is supported through a review of empirical literature both within sleepwalking and violent behaviour more generally. Biological, psychological and social risk factors are hypothesised to mediate the relationship between sleepwalking and violence. Implications for prevention and treatment of this potentially fatal problem are discussed.

DECLARATION OF INTEREST

None.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.

Medication induced sleepwalking: A systematic review

Medications that trigger sleepwalking may inadvertently put the patient at risk of injury to themselves and/or others, and contribute to poor treatment adherence. The aim of this study was to systematically review the literature to identify drugs that may increase the risk of sleepwalking. A search of CINAHL, EMBASE, PsycINFO, PubMed, and ScienceDirect was conducted with the keywords 'sleepwalking' OR 'somnambulism'. Of the original 83 sourced papers, 62 met the inclusion criteria and were subsequently included for review. Twenty-nine drugs, primarily in four classes-benzodiazepine receptor agonists and other gamma aminobutyric acid (GABA) modulators, antidepressants and other serotonergic agents, antipsychotics, and β-blockers-were identified as possible triggers for sleepwalking. The strongest evidence for medication-induced sleepwalking was for zolpidem and sodium oxybate. All other associations were based on case reports. This research highlights the importance of considering sleepwalking in risk profiles in clinical trials, particularly for drugs that enhance GABA activity at the GABA_A receptor, enhance serotonergic activity, or block the activity of noradrenaline at β receptors. The results also have implications for prescribers to consider sleepwalking as a potential adverse effect and ensure that: 1) the patient is educated about a safe sleep environment; 2) they are encouraged to report the onset or exacerbation of sleepwalking, and 3) alternative treatments are considered if sleepwalking occurs.

What Is the Link Between Hallucinations, Dreams, and Hypnagogic-Hypnopompic Experiences?

By definition, hallucinations occur only in the full waking state. Yet similarities to sleep-related experiences such as hypnagogic and hypnopompic hallucinations, dreams and parasomnias, have been noted since antiquity. These observations have prompted researchers to suggest a common aetiology for these phenomena based on the neurobiology of rapid eye movement (REM) sleep. With our recent understanding of hallucinations in different population groups and at the neurobiological, cognitive and interpersonal levels, it is now possible to draw comparisons between the 2 sets of experiences as never before. In the current article, we make detailed comparisons between sleep-related experiences and hallucinations in Parkinson's disease, schizophrenia and eye disease, at the levels of phenomenology (content, sensory modalities involved, perceptual attributes) and of brain function (brain activations, resting-state networks, neurotransmitter action). Findings show that sleep-related experiences share considerable overlap with hallucinations at the level of subjective descriptions and underlying brain mechanisms. Key differences remain however: (1) Sleep-related perceptions are immersive and largely cut off from reality, whereas hallucinations are discrete and overlaid on veridical perceptions; and (2) Sleep-related perceptions involve only a subset of neural networks implicated in hallucinations, reflecting perceptual signals processed in a functionally and cognitively closed-loop circuit. In summary, both phenomena are non-veridical perceptions that share some phenomenological and neural similarities, but insufficient evidence exists to fully support the notion that the majority of hallucinations depend on REM processes or REM intrusions into waking consciousness.