Is there a common motor dysregulation in sleepwalking and REM sleep behaviour disorder?

This study sought to determine if there is any overlap between the two major non‐rapid eye movement and rapid eye movement parasomnias, i.e. sleepwalking/sleep terrors and rapid eye movement sleep behaviour disorder. We assessed adult patients with sleepwalking/sleep terrors using rapid eye movement sleep behaviour disorder screening questionnaires and determined if they had enhanced muscle tone during rapid eye movement sleep. Conversely, we assessed rapid eye movement sleep behaviour disorder patients using the Paris Arousal Disorders Severity Scale and determined if they had more N3 awakenings. The 251 participants included 64 patients with rapid eye movement sleep behaviour disorder (29 with idiopathic rapid eye movement sleep behaviour disorder and 35 with rapid eye movement sleep behaviour disorder associated with Parkinson's disease), 62 patients with sleepwalking/sleep terrors, 66 old healthy controls (age‐matched with the rapid eye movement sleep behaviour disorder group) and 59 young healthy controls (age‐matched with the sleepwalking/sleep terrors group). They completed the rapid eye movement sleep behaviour disorder screening questionnaire, rapid eye movement sleep behaviour disorder single question and Paris Arousal Disorders Severity Scale. In addition, all the participants underwent a video‐polysomnography. The sleepwalking/sleep terrors patients scored positive on rapid eye movement sleep behaviour disorder scales and had a higher percentage of ‘any’ phasic rapid eye movement sleep without atonia when compared with controls; however, these patients did not have higher tonic rapid eye movement sleep without atonia or complex behaviours during rapid eye movement sleep. Patients with rapid eye movement sleep behaviour disorder had moderately elevated scores on the Paris Arousal Disorders Severity Scale but did not exhibit more N3 arousals (suggestive of non‐rapid eye movement parasomnia) than the control group. These results indicate that dream‐enacting behaviours (assessed by rapid eye movement sleep behaviour disorder screening questionnaires) are commonly reported by sleepwalking/sleep terrors patients, thus decreasing the questionnaire's specificity. Furthermore, sleepwalking/sleep terrors patients have excessive twitching during rapid eye movement sleep, which may result either from a higher dreaming activity in rapid eye movement sleep or from a more generalised non‐rapid eye movement/rapid eye movement motor dyscontrol during sleep.     

Alcohol-induced sleepwalking or confusional arousal as a defense to criminal behavior: a review of scientific evidence, methods and forensic considerations

An increasing number of criminal cases have claimed the defendant to be in a state of sleepwalking or related disorders induced by high quantities of alcohol. Sleepwalkers who commit violent acts, sexual assaults and other criminal acts are thought to be in a state of automatism, lacking conscious awareness and criminal intent. They may be acquitted in criminal trials. On the other hand, criminal acts performed as the result of voluntary alcohol intoxication alone cannot be used as a complete defense. The alcohol-induced sleepwalking criminal defense is most often based on past clinical or legal reports that ingestion of alcohol directly 'triggers' sleepwalking or increased the risk of sleepwalking by increasing the quantity of slow wave sleep (SWS). A review of the sleep medicine literature found no sleep laboratory studies of the effects of alcohol on the sleep of clinically diagnosed sleepwalkers. However, 19 sleep laboratory studies of the effects of alcohol on the sleep of healthy non-drinkers or social drinkers were identified with none reporting a change in SWS as a percentage of total sleep time. However, in six of 19 studies, a modest but statistically significant increase in SWS was found in the first 2-4 h. Among studies of sleep in alcohol abusers and abstinent abusers, the quantity and percentage of SWS was most often reduced and sometimes absent. Claims that direct alcohol provocation tests can assist in the forensic assessment of these cases found no support of any kind in the medical literature with not a single report of testing in normative or patient groups and no reports of validation testing of any sort. There is no direct experimental evidence that alcohol predisposes or triggers sleepwalking or related disorders. A legal defense of sleepwalking resulting from voluntarily ingested alcohol should be consistent with the current state of art sleep science and meet generally accepted requirements for the diagnosis of sleepwalking and other parasomnias.     

Arousal reactions in sleepwalking and night terrors in adults: the role of respiratory events

STUDY OBJECTIVES: The aim of the study was to determine the role of respiratory events, assessed by means of esophageal pressure monitoring, during arousals from slow wave sleep in adult patients with parasomnias. DESIGN: N/A. SETTING: N/A. PATIENTS: Ten patients with parasomnias (sleepwalking, night terrors, or both) and 10 control subjects matched for gender and age underwent 3 consecutive nights of polysomnography. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: By increasing sleep fragmentation, esophageal pressure monitoring has a deleterious effect on sleep architecture in patients with parasomnias and in control subjects. Respiratory events occur more frequently in parasomniacs than in controls. Respiratory effort seems to be responsible for the occurrence of a great number of arousal reactions in parasomniacs and is involved in triggering the parasomnia episodes. CONCLUSION: Sleep-disordered breathing seems to be frequently associated with parasomnias during slow wave sleep, emphasizing the utility of performing esophageal pressure monitoring in cases of sleep walking or night terrors.     

Violent somnambulism: A parasomnia of young men with stereotyped dream-like experiences

Objective

To characterize a subgroup of arousal parasomnias associated with violent behavior in adults.

Design

A pilot study on clinical and polysomnographic data of 13 adult patients seen in a tertiary sleep center for the suspicion of arousal parasomnia associated with violence.

Results

Nine young patients (8 males 1 female) had a common pattern of abnormalities: similar ‘claustrophobic’ dream-like experiences and complex, vehement dream enactments; no REM sleep without atonia on polysomnography. We call this syndrome ‘violent somnambulism’.The rest of the patients had alcoholic delirium, partial epilepsy, possible REM sleep behavior disorder and a single sleep walking episode provoked by a sleeping pill.

Conclusions and hypothesis

Sleep related violence needs thorough diagnostic evaluation for preventing life-threatening consequences. Violent somnambulism appears to be a distinct NREM sleep-related overlap parasomnia.     

Are microarousals preceded by electroencephalographic slow wave synchronization precursors of confusional awakenings?

The number of microarousals preceded by electroencephalographic (EEG) slow wave synchronization (MAS) and the number not preceded by EEG slow wave synchronization (K-complexes and/or delta groups) (MA) were analyzed during the first night of sleep in nine young patients with somnambulism and/or sleep terrors and in eight age- and sex-matched controls. While MAs peaked in REM ad intermediate sleep, MASs appeared as a phenomenon of NREM sleep, peaking in stage 2. The number of MASs was significantly greater in all stages of NREM sleep in the patient group, but number and distribution of MAs did not differ between the two groups. In the patient group, the MASs occurred in slow wave sleep (stages 3-4 of each sleep cycle); in controls, MASs occurred infrequently. MASs were frequently associated with automatic chewing movements. The higher frequency of microarousals in the patient group did not result in an increase in time awake during the night. The increase in number of microarousals supports Broughton's hypothesis of the presence of some "arousal disorder" in somnambulism and/or sleep terrors. MASs may be predictive markers of ensuing confusional awakenings.     

Is sleep‐related verbal memory consolidation impaired in sleepwalkers?

In order to evaluate verbal memory consolidation during sleep in subjects experiencing sleepwalking or sleep terror, 19 patients experiencing sleepwalking/sleep terror and 19 controls performed two verbal memory tasks (16‐word list from the Free and Cued Selective Reminding Test, and a 220‐ and 263‐word modified story recall test) in the evening, followed by nocturnal video polysomnography (n = 29) and morning recall (night‐time consolidation after 14 h, n = 38). The following morning, they were given a daytime learning task using the modified story recall test in reverse order, followed by an evening recall test after 9 h of wakefulness (daytime consolidation, n = 38). The patients experiencing sleepwalking/sleep terror exhibited more frequent awakenings during slow‐wave sleep and longer wakefulness after sleep onset than the controls. Despite this reduction in sleep quality among sleepwalking/sleep terror patients, they improved their scores on the verbal tests the morning after sleep compared with the previous evening (+16 ± 33%) equally well as the controls (+2 ± 13%). The performance of both groups worsened during the daytime in the absence of sleep (?16 ± 15% for the sleepwalking/sleep terror group and ?14 ± 11% for the control group). There was no significant correlation between the rate of memory consolidation and any of the sleep measures. Seven patients experiencing sleepwalking also sleep‐talked during slow‐wave sleep, but their sentences were unrelated to the tests or the list of words learned during the evening. In conclusion, the alteration of slow‐wave sleep during sleepwalking/sleep terror does not noticeably impact on sleep‐related verbal memory consolidation.     

Analysis of postarousal EEG activity during somnambulistic episodes

Early studies found that electroencephalographic (EEG) recordings during somnambulistic episodes were characterized by a combination of alpha, theta, and delta frequencies, without evidence of clear wakefulness. Three postarousal EEG patterns associated with slow-wave sleep (SWS) arousals were recently identified in adults with sleepwalking and sleep terrors. The goal of the present study was to evaluate the distribution of these postarousal EEG patterns in 10 somnambulistic patients (three males, seven females, mean age: 25.1, SD: 4.1) evaluated at baseline and following 38 h of sleep deprivation. A total of 44 behavioral arousals were recorded in the laboratory; seven episodes at baseline (five from SWS, two from stage 2 sleep) and 37 episodes during recovery sleep (30 from SWS, seven from stage 2 sleep). There was no significant difference in the distribution of postarousal EEG patterns identified during baseline and recovery sleep. One pattern, comprised of diffuse rhythmic and synchronous delta activity, was preferentially associated with relatively simple behavioral episodes but did not occur during episodes from stage 2 sleep. Overall, delta activity was detected in 48% of the behavioral episodes from SWS and in 22% of those from stage 2. There was no evidence of complete awakening during any of the episodes. The results support the view of somnambulism as a disorder of arousal and suggest that sleepwalkers' atypical arousal reactions can manifest themselves in stage 2 sleep in addition to SWS.     

Video polysomnographic findings in non‐rapid eye movement parasomnia

Although video polysomnography (vPSG) is not routinely recommended for the evaluation of typical cases of non‐rapid eye movement (NREM) parasomnias, it can aid diagnosis of unusual cases, other sleep disorders and complicated cases with REM behaviour disorder (RBD), and in differentiating parasomnias from epilepsy. In this study, we aimed to assess vPSG findings in consecutive patients with a clinical diagnosis of NREM‐parasomnia covering the whole phenotypic spectrum. Five hundred and twelve patients with a final diagnosis of NREM parasomnia who had undergone vPSG were retrospectively identified. vPSGs were analysed for features of NREM parasomnia and for the presence of other sleep disorders. Two hundred and six (40.0%) patients were clinically diagnosed with sleepwalking, 72 (14.1%) with sleep terrors, 39 (7.6%) with confusional arousals, 15 (2.9%) with sexsomnia, seven (1.4%) with sleep‐related eating disorder, 122 (23.8%) with mixed phenotype, and 51 (10.0%) with parasomnia overlap disorder (POD). The vPSG supported the diagnosis of NREM parasomnia in 64.4% of the patients and of POD in 98%. In 28.9% of the patients, obstructive sleep apnea (OSA) or/and periodic limb movements during sleep (PLMS) were identified, most commonly in older, male, sleepy and obese patients. vPSG has a high diagnostic yield in patients with NREM parasomnia and should be routinely performed when there is diagnostic doubt, or in patients where there is a suspicion of OSA and PLMS.     

Arousal norms for children age 5-16 years based on home polysomnography.

Fragmentation of sleep by brief arousals has become an acknowledged aspect of poor quality sleep but there is a shortage of normative data on such arousals, especially for children. Norms for arousals (defined according to American Sleep Disorders Association criteria) were compiled for 61 children age 5-16 years using the Oxford Medilog system for a single night of home polysomnography. No significant differences were seen between the five age subgroups considered in average number of arousals per hour of sleep although individual differences were apparent at each age level and arousal duration was somewhat longer at younger ages. The low arousal rates in the children studied are in keeping with other evidence that arousal rates increase throughout life. Boys were no different from girls in either arousal frequency or duration. Arousal frequency was correlated with PSG awakenings but only to a modest extent. These new normative values should be useful in clinical practice and research for the assessment of the quality of children's sleep.     

Evidence of Dissociated Arousal States During NREM Parasomnia from an Intracerebral Neurophysiological Study

Study Objectives:

Arousal parasomnias are expressions of sleep/wake state dissociations in which wakefulness and NREM sleep seem to coexist. We describe the results of a neurophysiological (intracerebral EEG) investigation that captured an episode of confusional arousal.

Design:

Observational analysis.

Setting:

Tertiary sleep center.

Subject:

A 20-year-old male with refractory focal epilepsy.

Measurements and Results:

The intracerebral EEG findings documented the presence of a local arousal of the motor and cingulate cortices associated with increased delta activity in the frontoparietal associative cortices; these findings were noted preceding the onset and persisting throughout the episode.

Conclusions:

The presence of dissociated sleep/wake states in confusional arousals is the expression not of a global phenomenon, but rather of the coexistence of different local states of being: arousal of the motor and cingulate cortices and inhibition of the associative ones. Whether this is an exclusive feature of NREM parasomnias, or a common substrate on which other triggering elements act, needs to be clarified.

Citation:

Terzaghi M; Sartori I; Tassi L; Didato G; Rustioni V; LoRusso G; Manni R; Nobili L. Evidence of dissociated arousal states during NREM parasomnia from an intracerebral neurophysiological study. SLEEP 2009;32(3):409–412.     

Sleep and sex: what can go wrong? A review of the literature on sleep related disorders and abnormal sexual behaviors and experiences

STUDY OBJECTIVES: To formulate the first classification of sleep related disorders and abnormal sexual behaviors and experiences. DESIGN: A computerized literature search was conducted, and other sources, such as textbooks, were searched. RESULTS: Many categories of sleep related disorders were represented in the classification: parasomnias (confusional arousals/sleepwalking, with or without obstructive sleep apnea; REM sleep behavior disorder); sleep related seizures; Kleine-Levin syndrome (KLS); severe chronic insomnia; restless legs syndrome; narcolepsy; sleep exacerbation of persistent sexual arousal syndrome; sleep related painful erections; sleep related dissociative disorders; nocturnal psychotic disorders; miscellaneous states. Kleine-Levin syndrome (78 cases) and parasomnias (31 cases) were most frequently reported. Parasomnias and sleep related seizures had overlapping and divergent clinical features. Thirty-one cases of parasomnias (25 males; mean age, 32 years) and 7 cases of sleep related seizures (4 males; mean age, 38 years) were identified. A full range of sleep related sexual behaviors with self and/or bed partners or others were reported, including masturbation, sexual vocalizations, fondling, sexual intercourse with climax, sexual assault/rape, ictal sexual hyperarousal, ictal orgasm, and ictal automatism. Adverse physical and/or psychosocial effects from the sleepsex were present in all parasomnia and sleep related seizure cases, but pleasurable effects were reported by 5 bed partners and by 3 patients with sleep related seizures. Forensic consequences were common, occurring in 35.5% (11/31) of parasomnia cases, with most (9/11) involving minors. All parasomnias cases reported amnesia for the sleep-sex, in contrast to 28.6% (2/7) of sleep related seizure cases. Polysomnography (without penile tumescence monitoring), performed in 26 of 31 parasomnia cases, documented sexual moaning from slow wave sleep in 3 cases and sexual intercourse during stage 1 sleep/wakefulness in one case (with sex provoked by the bed partner). Confusional arousals (CAs) were diagnosed as the cause of "sleepsex" ("sexsomnia") in 26 cases (with obstructive sleep apnea [OSA] comorbidity in 4 cases), and sleepwalking in 2 cases, totaling 90.3% (28/31) of cases being NREM sleep parasomnias. REM behavior disorder was the presumed cause in the other 3 cases. Bedtime clonazepam therapy was effective in 90% (9/10) of treated parasomnia cases; nasal continuous positive airway pressure therapy was effective in controlling comorbid OSA and CAs in both treated cases. All five treated patients with sleep related sexual seizures responded to anticonvulsant therapy. The hypersexuality in KLS, which was twice as common in males compared to females, had no reported effective therapy. CONCLUSIONS: A broad range of sleep related disorders associated with abnormal sexual behaviors and experiences exists, with major clinical and forensic consequences.     

Behavioural and emotional profiles of children and adolescents with disorders of arousal

Disorders of arousals are common sleep disorders characterized by complex motor behaviours that arise episodically out of slow‐wave sleep. Psychological distress has long been associated with disorders of arousal, but this link remains controversial, especially in children and adolescents. The aim of this multi‐centre study was to characterize behavioural and emotional problems in a sample of children/adolescents with disorders of arousal, and to explore their relationship with the severity of nocturnal episodes. The parents of 41 children/adolescents with a diagnosis of disorders of arousal (11.5 ± 3.3 years old, 61% males) and of a group of 41 age‐ and gender‐matched control participants filled in the Child Behavior Checklist, along with the Sleep Disturbance Scale for Children and the Paris Arousal Disorders Severity Scale. Multilevel t‐tests revealed significantly higher total scores and sub‐scores of the Child Behavior Checklist for the patient group compared with the control group. Thirty‐four percent of the patients obtained pathological total scores, and 12% of them borderline scores. The severity of emotional/behavioural problems in the patient group was positively correlated with the severity of the nocturnal episodes. Interestingly, children/adolescents with disorders of arousal also obtained higher excessive daytime sleepiness and insomnia symptoms sub‐scores at the Sleep Disturbance Scale for Children. These results confirmed the hypothesis that behavioural/emotional problems are surprisingly common in children/adolescents with disorders of arousal. Further studies are warranted to investigate the causal relationship between pathological manifestations, subtler sleep abnormalities, and diurnal emotional/behavioural problems in children/adolescents with disorders of arousal.     

Am I (hyper)aroused or anxious? Clinical significance of pre‐sleep somatic arousal in young adults

Self‐reported somatic arousal remains a challenging clinical construct, particularly because only a subset of patients report symptoms such as racing heart, palpitations or increased body temperature interfering with their sleep. It is unclear whether self‐reported somatic arousal is a marker of hyperarousal or co‐morbid clinical anxiety in individuals with insomnia. Participants included 196 young adults aged 20.2 ± 1.0 years old who were predominantly females (75%). About 39% of the sample reported subthreshold insomnia, and about 8% reported clinically significant insomnia, based on their Insomnia Severity Index. Participants completed the Pre‐Sleep Arousal Scale, Beck Anxiety Inventory, Beck Depression Inventory, Arousal Predisposition Scale, and Ford Insomnia Response to Stress Test. Multivariable stepwise regression assessed which factors were independently associated with pre‐sleep cognitive (Pre‐Sleep Arousal Scale‐Cognitive) and somatic (Pre‐Sleep Arousal Scale‐Somatic) arousal. Receiver‐operating characteristic analysis assessed the predictive value to identify clinically significant anxiety (Beck Anxiety Inventory ≥ 20), insomnia (Insomnia Severity Index ≥ 15) and arousability (Arousal Predisposition Scale ≥ 32). Beck Anxiety Inventory (β = 0.42) was the best single correlate of Pre‐Sleep Arousal Scale‐Somatic, while Insomnia Severity Index (β = 0.33) was of Pre‐Sleep Arousal Scale‐Cognitive. A Pre‐Sleep Arousal Scale‐Somatic score of 12 or more identified those with clinically significant anxiety with 65% specificity and 65% sensitivity, while a cut‐off score of 14 increased its sensitivity (86%). Self‐reported pre‐sleep somatic arousal may be an index of co‐morbid clinical anxiety in individuals with insomnia. These findings aid clinicians with assessment and treatment, particularly in the absence of clinical guidelines indicating when somatically focused relaxation techniques should be included as part of multicomponent cognitive behavioural treatment of insomnia.     

The carotid body and arousal in the fetus and neonate

Arousal from sleep is a major defense mechanism in infants against hypoxia and/or hypercapnia. Arousal failure may be an important contributor to SIDS. Areas of the brainstem that have been found to be abnormal in a majority of SIDS infants are involved in the arousal process. Arousal is sleep state dependent, being depressed during AS in most mammals, but depressed during QS in human infants. Repeated exposure to hypoxia causes a progressive blunting of arousal that may involve medullary raphe GABAergic mechanisms. Whereas CB chemoreceptors contribute heavily to arousal in response to hypoxia, serotonergic central chemoreceptors have been implicated in the arousal response to CO₂. Pulmonary or chest wall mechanoreceptors also contribute to arousal in proportion to the ventilatory response and decreases in their input may contribute to depressed arousal during AS. Little is known about specific arousal pathways beyond the NTS. Whether CB chemoreceptor stimulation directly stimulates arousal centers or whether this is done indirectly through respiratory networks remains unknown. This review will focus on arousal in response to hypoxia and CO₂ in the fetus and newborn and will outline what we know (and do not know) about the involvement of the carotid body in this process.     

Sleep problems and daytime somnolence in a German population-based sample of snoring school-aged children

Habitual snoring is associated with daytime symptoms like tiredness and behavioral problems. Its association with sleep problems is unclear. We aimed to assess associations between habitual snoring and sleep problems in primary school children. The design was a population-based cross-sectional study with a nested cohort study. The setting was twenty-seven primary schools in the city of Hannover, Germany. Habitual snoring and sleep problems were assessed in primary school children using an extended version of Gozal's sleep-disordered breathing questionnaire (n = 1144). Approximately 1 year later, parents of children reported to snore habitually (n = 114) and an equal number of children who snored never or occasionally were given the Sleep Disturbance Scale for Children, a validated questionnaire for the assessment of pediatric sleep problems. Snoring status was re-assessed using the initial questionnaire and children were then classified as long-term habitual snorers or ex-habitual snorers. An increasing prevalence of sleep problems was found with increasing snoring frequency for sleep-onset delay, night awakenings, and nightmares. Long-term habitual snorers were at significantly increased risk for sleep-wake transition disorders (e.g. rhythmic movements, hypnic jerks, sleeptalking, bruxism; odds ratio, 95% confidence interval: 12.0, 3.8-37.3), sleep hyperhidrosis (3.6, 1.2-10.8), disorders of arousal/nightmares (e.g. sleepwalking, sleep terrors, nightmares; 4.6, 1.3-15.6), and excessive somnolence (i.e. difficulty waking up, morning tiredness, daytime somnolence; 6.3, 2.2-17.8). Ex-habitual snorers were at increased risk for sleep-wake transition disorders (4.4, 1.4-14.2). Habitual snoring was associated with several sleep problems in our study. Long-term habitual snorers were more likely to have sleep problems than children who had stopped snoring spontaneously.     

Effects of cognitive arousal and physiological arousal on sleep perception

STUDY OBJECTIVES: Two experiments were conducted to investigate the effect of presleep arousal on sleep perception. Experiment 1 examined the link between presleep cognitive arousal and distorted perception of sleep and compared the relative effect of anxious and neutral cognitive arousal on sleep perception. Experiment 2 compared the relative effect of anxious cognitive arousal and physiological arousal on sleep perception. DESIGN: Participants completed a nap session. Just prior to the nap, the participants were randomly assigned to 1 of 3 groups to receive different arousal manipulations. They were then allowed to go to sleep and were asked to report their sleep perception upon waking. SETTING: Sleep laboratory. PARTICIPANTS: Fifty-four healthy good sleepers in each experiment. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Self-reported sleep, actigraphy-defined sleep, and the discrepancy between them were indexed. In Experiment 1, participants who were experimentally manipulated to experience anxious cognitive arousal during the presleep period reported longer sleep-onset latency. Both the Anxious Cognitive Arousal Group and the Neutral Cognitive Arousal Group exhibited a greater discrepancy between self-reported and actigraphy-defined sleep, relative to participants who received no manipulation. In Experiment 2, participants who were experimentally manipulated to experience anxious cognitive arousal or physiological arousal during the presleep period reported longer sleep-onset latency and shorter total sleep time, and both groups exhibited a greater discrepancy between the self-reported and actigraphy-defined sleep, relative to participants who received no manipulation. CONCLUSIONS: Results suggest that both presleep cognitive arousal and presleep physiological arousal contribute to distorted perception of sleep.     

Relationship of arousal threshold to sleep stage distribution and subjective estimates of depth and quality of sleep.

The relationship of arousal threshold, amounts of various sleep stages, and subjective rating of sleep was studied in two separate experiments involving 7 and 26 young adult subjects, respectively. Electroencephalographic sleep stage data, subjective response data, and arousal threshold data were collected over a series of nights in the sleep laboratory. Only nonsignificant relationships were found between magnitude of arousal threshold and amounts of various sleep stages or subjective rating of sleep quality in between-subjects analyses. However, when the nights representing extremes in arousal threshold were examined within-subject, it was found that nights of high threshold were accompanied by subjective reports of significantly better sleep in both studies and by a significant decrease in the amount of stage W in one study. Arousal threshold was not related to subjective depth of sleep in either study. Rather, subjective ratings of depth of sleep were significantly related to the amount of EEG-defined wakefulness and stage 1.     

The cardiorespiratory activation response at an arousal from sleep is independent of the level of CO(2)

Arousal from sleep is associated with transient cardiorespiratory activation. Traditionally, this response has been understood to be a consequence of state-dependent changes in the homeostatic control of ventilation. The hypothesis predicts that the magnitude of ventilatory and cardiac responses at an arousal will be a function of the intensity of concurrent respiratory stimuli (primarily PCO(2)). Alternatively, it has been proposed that increased cardiorespiratory activity is due to reflex activation. This hypothesis predicts that the magnitude of the cardiorespiratory response will be independent of respiratory stimuli. To compare these hypotheses we measured minute ventilation (V(i)), heart rate (HR) and blood pressure (BP) during wakefulness and stage 2 sleep, while manipulating P(et)CO(2). Further, we assessed the magnitude of the response of these variables to an arousal from sleep at the various levels of P(et)CO(2). The subjects were male aged 18-25 years. P(et)CO(2) was manipulated by clamping it at four levels during wakefulness [wake eucapnic, sleep eucapnic (Low), and sleep eucapnic +3 mmHg (Medium) and +6 mmHg (High)] and three levels during sleep (Low, Medium and High). The average number of determinations for each subject at each level was 14 during wakefulness and 25 during sleep. Arousals were required to meet American Sleep Disorders Association criteria and were without body movement. The results indicated that average increases in V(i), HR and BP at arousal from sleep did not significantly differ as a function of the level of P(et)CO(2) present at the time of the arousal (all P > 0.05). Further, the magnitude of the ventilatory response to an arousal was significantly less than the values predicted by the homeostatic hypothesis (P < 0.05). We conclude that, in normal subjects, the cardiorespiratory response to an arousal from sleep is not because of a homeostatic response, but of a reflex activation.     

Association between childhood sleep problems and perinatal factors, parental mental distress and behavioral problems

The aim of this study was to examine the effect of age, gender and perinatal risk factors on the risks for sleep problems, and investigate the relation between childhood sleep problems and children's behavioral syndromes and parental mental distress in early and middle childhood. We recruited a representative sample of 1391 children, ages 4-9, from nine kindergartens and three elementary schools by using a multistage sampling method. Parents of child participants completed a questionnaire including perinatal risk factors, sleep habits and problems, the Child Behavior Checklist (CBCL) and the Chinese Health Questionnaire (CHQ). A mixed model was used for data analysis to address cluster effect from the same classes and schools. Results showed that boys suffered from more sleep problems than girls. Early insomnia, sleep terrors and enuresis decreased with ages, but sleepwalking increased with ages. Perinatal exposure to alcohol, coffee and non-prescribed medication, vaginal bleeding, artificial delivery, first-born order and higher parental CHQ score (> or =4) were significantly associated with several childhood sleep problems. In addition, children with sleep problems had higher T-scores of the eight behavioral syndromes derived from the CBCL. Our findings indicated that the childhood sleep problems were associated with perinatal risk factors, parental psychopathology and children's behavioral problems.     

Dissociated local arousal states underlying essential clinical features of non-rapid eye movement arousal parasomnia: an intracerebral stereo-electroencephalographic study

Sleep has been shown to be a global phenomenon in which the presence of local processes of both activation and deactivation are finely orchestrated. Dysfunctional and independent action of the systems involved in non-rapid eye movement (NREM) sleep and wakefulness is deemed to be at the basis of arousal parasomnias. We show, in a patient with confusional arousals, persistence of sleep in the hippocampal and frontal associative cortices in contrast to the presence of awakening in the motor, cingulate, insular, amygdalar and temporopolar cortices. The clinical features of the confusional arousals in this patient are highly consistent with a dysfunctional coexistence of local cortical arousal and local cortical sleep.