Nocturnal enuresis in children: prevalence, correlates, and relationship with obstructive sleep apnea.

OBJECTIVES: To examine the prevalence and correlates of nocturnal enuresis (NE) in primary school children, and to compare the prevalence of NE in children with and those without obstructive sleep apnea (OSA). STUDY DESIGN: Parents of children aged 6-11 years completed a questionnaire eliciting information on sleep-related symptoms, demography, and family and past medical history. Children screened due to high risk for OSA, along with a randomly chosen low-risk group, underwent overnight polysomnography (PSG). RESULTS: A total of 6147 children (3032 girls) were studied. The overall prevalence of NE (≥1 wet night/month) was 4.6% (6.7% of boys and 2.5% of girls). Boys had a significantly greater prevalence across all age groups. In 597 children (215 girls) who underwent PSG, the prevalence of NE was not greater in children with OSA, but was increased with increasing severity of OSA in girls only. Boys with NE had longer deep sleep duration. Sex and sleep-related symptoms were associated with NE. CONCLUSIONS: This community-based study demonstrated a sex-associated prevalence of NE in relation to increasing OSA severity.

Epidemiology of obstructive sleep apnoea syndrome in Chinese children: a two-phase community study.

OBJECTIVE: To determine the prevalence and risk factors of obstructive sleep apnoea syndrome (OSAS) in Chinese children using a two-phase community-based study design. METHODS: Children from 13 primary schools were randomly recruited. A validated OSAS screening questionnaire was completed by their parents. Children at high risk of OSAS and a randomly chosen low-risk group were invited to undergo overnight polysomnographic study and clinical examination. The the sex-specific prevalence rate was measured using different cutoffs (obstructive apnoea hypopnoea index ≥ 1, ≥ 1.5, ≥ 3 and ≥ 5 and obstructive apnoea index ≥ 5) and risk factors associated with OSAS were evaluated with logistic regression. RESULTS: 6447 completed questionnaires were returned (out of 9172 questionnaires; 70.3%). 586 children (9.1%; 405 boys and 181 girls) children belonged to the high-risk group. A total of 619 (410 and 209 from the high and low-risk group, respectively) subjects underwent overnight polysomnagraphy. Depending on the cutoffs, the prevalence rate of childhood OSAS varied from 4.8% to 40.3%. Using the International Criteria of Sleep Disorders version II, the OSAS prevalence for boys and girls was 5.8% and 3.8%, respectively. Male gender, body mass index z-score and increased adenoid and tonsil size were independently associated with OSAS. CONCLUSIONS: The prevalence rate of OSAS in children was contingent on the cutoff used. The inclusion of symptoms as a part of the diagnostic criteria greatly reduced the prevalence. A further prospective and outcome study is needed to define a clinically significant diagnostic cutoff for childhood OSAS.

Periodic limb movement during sleep is associated with nocturnal hypertension in children.

BACKGROUND: Increasing evidence suggests that blood pressure (BP) is significantly influenced by sleep problems in children, but the association between periodic limb movement during sleep (PLMS) and BP is still unclear. This study aims to compare ambulatory blood pressure (ABP) in children with and without PLMS. METHODS AND RESULTS: A cross-sectional study involving 314 children (mean (SD) age of 10.4 (1.7) years, boys 62.4%). Participants underwent an overnight polysomnographic study and ABP monitoring. Subjects were hypertensive if mean SBP or DBP > 95th percentile and prehypertensive if mean SBP or DBP > 90th percentile of reference. Children with PLMS (n = 17) were at significantly higher risk for nocturnal systolic (adjusted OR (95%CI) = 6.25 [1.87-20.88]) and diastolic (OR (95%CI) = 4.83 [1.66-14.07]) hypertension. However, mean nocturnal BP did not differ between children with and without PLMS. There was a trend for higher daytime BP in patients with PLMS than those children without PLMS (P = 0.084 for systolic BP z score; P = 0.051 for diastolic BP z score; P = 0.067 for systolic prehypertension). There were significant associations between log transformed PLM index and daytime systolic and mean BP z scores (P = 0.03 and 0.033 respectively) as well as that between log transformed PLM related arousal index (PLMSArI) and nocturnal diastolic and mean BP (P = 0.008 and 0.038 respectively). CONCLUSIONS: PLMS was independently associated with a wide range of BP elevations, especially nocturnal indices. Future studies should examine the underlying pathophysiologic mechanisms and effects of PLMS treatment on BP.

Blood pressure is elevated in children with primary snoring.

OBJECTIVES: To compare ambulatory blood pressure (ABP) in nonoverweight, prepubertal children with and without primary snoring (PS), and to investigate whether PS is a part of the dose-response relationship between sleep-disordered breathing (SDB) and BP in children. STUDY DESIGN: This was a cross-sectional community-based study involving 190 children age 6 to 13 years. Each participant underwent an overnight sleep study and ABP monitoring after completing a validated sleep symptoms questionnaire. Individual systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial BP were calculated for wake and sleep periods. Subjects were hypertensive if mean SBP or DBP was > 95th percentile (relative to sex and height) of reference. RESULTS: A total of 56 nonsnoring controls, 46 children with PS, 62 children with an apnea-hypopnea index (AHI) of 1 to 3, and 26 children with an AHI > 3 were identified. The daytime and nighttime BP increased across the severity spectrum of SDB. The dose-response trends for the proportion of subjects with nighttime systolic and diastolic hypertension also were significant. Nighttime DBP was significantly higher in the children with PS compared with controls after adjusting for age, sex, and body mass index. CONCLUSIONS: PS was demonstrated to be an aspect of the dose-response relationship between SDB and BP in children and should not be considered completely benign.

Diagnosis of REM sleep behavior disorder by video-polysomnographic study: is one night enough?

STUDY OBJECTIVES: Clinical features of RBD were typically episodic with limited data on the night-to-night reliability of the diagnostic video-PSGs. We aimed to assess on whether a single night study was adequate. DESIGN: Retrospective review. SETTING: Sleep laboratory. PARTICIPANTS: 55 RBD patients with at least 2 consecutive video-PSGs. INTERVENTIONS: N/A. METHODS: We analyzed 2 consecutive video-PSGs using REM-related EMG activity (REMREEA), REM sleep without atonia (RSWA), and video analysis of motor events. MEASUREMENTS AND RESULTS: A weak first night effect with increased REM sleep latency, increased stage 1 sleep, and increased arousal index were found. No differences were found in phasic and tonic EMG activity scores between night 1 and night 2. The presence of OSAS, use of CPAP, and clonazepam treatment did not affect the night-to-night variability and diagnostic accuracy. The kappas were 0.64, 0.51, and 0.31 between night 1 and night 2 for 10% REMREEA, RSWA, and video analysis respectively. Over 80% of patients could be diagnosed by various criteria in the first night, but the diagnostic ability could be enhanced to nearly 95% when combining PSG with video analysis. While both of the EMG criteria as well as the combination criteria had good reliability, video-analysis had poorer night-to-night reliability. CONCLUSIONS: A single night of video-PSG was adequate in the diagnosis of RBD in most clinical patients and the combination of PSG and video analysis could enhance the detection rate further. Our findings have important resource implications.

Validation of a questionnaire instrument for prediction of obstructive sleep apnea in Hong Kong Chinese children.

To develop and validate a questionnaire scale that can be used as a screening tool to investigate for the presence of childhood obstructive sleep apnea syndrome (OSAS) in Hong Kong Chinese children. Subjects suspected to have OSAS and controls were recruited. Parents completed a Hong Kong children sleep questionnaire (HK-CSQ) and all recruited subjects underwent at least one overnight polysomnographic study (PSG). An obstructive apnea index (OAI) >or= 1/h was diagnostic of OSAS. Receiver-operating characteristics (ROC) curve was constructed to determine optimal sensitivity and specificity. Reliability and validity of the questionnaire scale were also assessed. Two hundred twenty-nine children (149 boys and 80 girls) with a mean age of 10.0 years (SD = 2.1) were recruited. Their mean body mass index (BMI) and OAI were 19.8 (SD = 5.1) and 2.6 (SD = 7.6), respectively. Fifty-four boys and 12 girls were found to have OSAS. Three questions were found to be highly significant in predicting for the presence of OSAS-snoring, nocturnal mouth breathing, and sweating. A composite score of 7 from the three questions (range 0-12) was found to discriminate the OSAS cases best [ROC curve, AUC = 0.8 (95% CI = 0.8-0.9)]. The sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) were 75.4, 80.5, 61.3, and 88.9%, respectively. Test-retest reliability was undertaken in 51 subjects and the measurement of agreement (Kappa value) was 0.6. This HK-CSQ is a useful, valid, and reliable screening instrument for the presence of OSAS in children.

A prospective, naturalistic follow-up study of treatment outcomes with clonazepam in rapid eye movement sleep behavior disorder.

BACKGROUND: Rapid eye movement sleep behavior disorder (RBD) is characterized by prominent dream-enacting behaviors, often resulting in sleep-related injuries. OBJECTIVES: This study aimed to prospectively examine the treatment response of people with RBD treated with clonazepam, by quantitatively delineating the characteristic changes in the clinical and polysomnographic features, and to explore the factors associated with this response. METHODS: Patients diagnosed with idiopathic RBD (iRBD) were consecutively recruited and invited to complete clinical and polysomnographic (PSG) assessments and self-administered questionnaires (including the modified REM Sleep Behavior Questionnaire, RBDQ-3M) before and after the initiation of treatment with clonazepam. RESULTS: Thirty-nine iRBD patients (male: 74.4%, mean age at diagnosis: 68.3 ± 7.8 years) were recruited with a follow-up duration of 28.8 ± 13.3 months. Clonazepam was offered as the first-line treatment (starting dose: 0.43 ± 0.16 mg, range: 0.125-1.00; dose at follow-up: 0.98 ± 0.63 mg, range: 0.125-3). Treatment response, as defined by a complete elimination of sleep-related injuries and potentially injurious behaviors to self and/or to bed partner, at follow-up was reported in 66.7% of the overall study subjects. Frequency of disturbing dreams with violent and frightening content and vigorous behavioral RBD symptoms was significantly reduced, while residual nocturnal symptoms and an increase in REM-related EMG activities were observed at follow-up. Less optimal treatment outcomes were found to be associated with the presence of comorbid obstructive sleep apnea and earlier onset of RBD. CONCLUSIONS: Clonazepam differentially changes dream affect and content, as well as reduces vigorous verbal and motor behaviors. Residual RBD symptoms are common, despite treatment. Other more effective alternative or adjunctive interventions are needed for better clinical management of RBD.

Altered Sleep Stage Transitions of REM Sleep: A Novel and Stable Biomarker of Narcolepsy.

OBJECTIVES: To determine the diagnostic values, longitudinal stability, and HLA association of the sleep stage transitions in narcolepsy. METHODS: To compare the baseline differences in the sleep stage transition to REM sleep among 35 patients with type 1 narcolepsy, 39 patients with type 2 narcolepsy, 26 unaffected relatives, and 159 non-narcoleptic sleep patient controls, followed by a reassessment at a mean duration of 37.4 months. RESULTS: The highest prevalence of altered transition from stage non-N2/N3 to stage R in multiple sleep latency test (MSLT) and nocturnal polysomnography (NPSG) was found in patients with type 1 narcolepsy (92.0% and 57.1%), followed by patients with type 2 narcolepsy (69.4% and 12.8%), unaffected relatives (46.2% and 0%), and controls (39.3% and 1.3%). Individual sleep variables had varied sensitivity and specificity in diagnosing narcolepsy. By incorporating a combination of sleep variables, the decision tree analysis improved the sensitivity to 94.3% and 82.1% and enhanced specificity to 82.4% and 83% for the diagnosis of type 1 and type 2 narcolepsy, respectively. There was a significant association of DBQ1*0602 with the altered sleep stage transition (OR = 16.0, 95% CI: 1.7-149.8, p = 0.015). The persistence of the altered sleep stage transition in both MSLT and NPSG was high for both type 1 (90.5% and 64.7%) and type 2 narcolepsy (92.3% and 100%), respectively. CONCLUSION: Altered sleep stage transition is a significant and stable marker of narcolepsy, which suggests a vulnerable wake-sleep dysregulation trait in narcolepsy. Altered sleep stage transition has a significant diagnostic value in the differential diagnosis of hypersomnias, especially when combined with other diagnostic sleep variables in decision tree analysis.

Reduced striatal dopamine transmission in REM sleep behavior disorder comorbid with depression.

OBJECTIVE: To investigate dopamine transmission in patients with comorbid REM sleep behavior disorder (RBD) and major depressive disorder (MDD). METHODS: This is a case-control study including 11 medicated patients with comorbid RBD and MDD (mean age 47.5 ± 8.2), 8 medicated patients with MDD only (mean age 47.9 ± 8.4), and 10 healthy participants (mean age 46.5 ± 10.6 years). They underwent clinical assessment, video-polysomnography, olfactory tests, and neuroimaging studies ((18)F-DOPA, (11)C-raclopride, and (18)F-FDG PET neuroimaging). RESULTS: Compared with the 2 control groups, patients with comorbid RBD and MDD had significantly lower (18)F-DOPA uptake at 60 minutes in the putamen and caudate after controlling for age and sex effect (p < 0.05). There were no significant differences for the (11)C-raclopride and (18)F-FDG-PET. The (18)F-DOPA uptake in putamens had significant inverse correlation with severity of RBD symptoms (p < 0.01) and REM-related tonic muscle activity (p < 0.01). The comorbid RBD and MDD group had more impairment in olfactory function. CONCLUSION: Patients with comorbid RBD and MDD had presynaptic dopamine dysfunction and impaired olfactory function. There is a distinct possibility that the development of RBD symptoms among patients with MDD may represent an early phase of α-synucleinopathy neurodegeneration instead of a merely antidepressant-induced condition.

Is a 2-night polysomnographic study necessary in childhood sleep-related disordered breathing?

BACKGROUND AND OBJECTIVES: There are limited data on the night-to-night variability of childhood sleep-related disordered breathing (SDB). We aim to assess for the presence of first-night effect (FNE) and to examine whether a single-night sleep study is adequate in the assessment of childhood SDB. DESIGN: In a case-control study investigating whether obesity is a risk factor for childhood SDB, the night-to-night variability of sleep and respiratory variables were studied. PARTICIPANTS AND SETTING: Forty-six obese children from a pediatric obesity clinic and 44 age- and sex-matched normal weight control subjects from local schools. INTERVENTIONS: All subjects underwent two consecutive overnight polysomnographic studies. An obstructive apnea index (OAI) >/= 1/h was considered diagnostic of SDB. RESULTS: The mean age of the children was 11.21 years (SD 2.21). Forty-four obese children and 43 control subjects completed the 2-night study. Based on the criterion of the worst OAI over the 2 nights, 13 subjects were found to have SDB, 12 subjects were primary snorers, and 62 were normal subjects. In all subjects, the sleep efficiency improved and sleep-onset latency was reduced on the second night. While there was a rebound of rapid eye movement sleep with the associated worsening of respiratory indexes (mainly accounted for by an increase in central apneas and hypopneas) evident in normal subjects, there was a significant improvement of respiratory disturbances in the SDB group on the second night. The first-night polysomnography would have correctly identified 84.6% of cases as defined by the criteria of the worst OAI over the 2 nights. All cases missed by the first-night study had only borderline OAI. CONCLUSIONS: The phenomenon of FNE in children was well demonstrated in our study. We proposed that a single-night sleep study is adequate and more cost-effective in assessing for childhood SDB.

Acute and chronic effects of sleep duration on blood pressure.

OBJECTIVE: To evaluate the association between ambulatory blood pressure (ABP) and sleep duration as measured by 7-day sleep diary and nocturnal polysomnography in normal-weight adolescents without significant obstructive sleep apnea. METHODS: Subjects aged 10 to 17.9 years with an obstructive apnea hypopnea index <5 underwent polysomnography for 9.5 hours and 24-hour ABP monitoring commencing at noon on the same day. ABP was divided into prepolysomnography, in bed during polysomnography, and postpolysomnography periods for separate analyses. Sleep duration (SpD7) was obtained from a 7-day sleep diary, reflecting the sleep pattern in the week before admission. Total sleep time (TST) and sleep efficiency (SpE) were obtained from polysomnography. RESULTS: A total of 143 adolescents participated. SpD7 was inversely associated with systolic blood pressure (SBP) in prepolysomnography, in-bed, and postpolysomnography periods (all ß = -2 mm Hg) and with diastolic blood pressure (DBP) in prepolysomnography and in-bed periods (all ß = -1 mm Hg). TST was inversely associated with SBP in the postpolysomnography period (ß = -1.5 mm Hg). SpE was inversely associated with SBP in in-bed period (ß = -0.1 mm Hg) and with DBP in in-bed (ß = -0.1 mm Hg) and postpolysomnography (ß = -0.2 mm Hg) periods. Neither TST nor SpE was associated with SBP and DBP in prepolysomnography period. CONCLUSIONS: Short sleep duration as reflected by 7-day sleep diary was associated with higher blood pressure in normal-weight adolescents. Occasional adequate sleep may partially ameliorate the risk of high blood pressure but may not completely reverse the effect of long-term sleep insufficiency.

Sleep architecture in school-aged children with primary snoring.

OBJECTIVE: We aimed to examine if sleep architecture was altered in school-aged children with primary snoring (PS). METHODS: Children ages 6 to 13 years from 13 primary schools were randomly recruited. A validated obstructive sleep apnea (OSA) screening questionnaire was completed by their parents. Children at high risk for OSA and a randomly chosen low-risk group were invited to undergo overnight polysomnography (PSG) and clinical examination. Participants were classified into healthy controls, PS, mild OSA, and moderate to severe OSA (MS OSA) groups for comparison. RESULTS: A total of 619 participants underwent PSG (mean age, 10.0 ± 1.8 years; 396 (64.0%) boys; 524 (84.7%) prepubertal). For the cohort as a whole, there were no significant differences in measures of sleep architecture between PS and nonsnoring healthy controls. In the multiple regression model, percentage of nonrapid eye movement (NREM) stage 1 (N1) sleep had a significantly positive association, whereas percentage of slow-wave sleep (SWS) had a significantly negative association with sleep-disordered breathing (SDB) severity after controlling for age, gender, body mass index (BMI) z score, and pubertal status. In prepubertal children with PS, no significant disruption of sleep architecture was found. However, pubertal adolescent PS participants had significantly higher adjusted percentage of N1 sleep and wake after sleep onset (WASO) compared to healthy controls. CONCLUSIONS: PS did not exert significant adverse influences on normal sleep architecture in prepubertal school-aged children. Nevertheless, pubertal adolescents with PS had increased N1 sleep and WASO.

A 4-year prospective follow-up study of childhood OSA and its association with BP.

BACKGROUND: Childhood OSA is a prevalent condition associated with raised BP as documented in cross-sectional studies. This study aimed to determine whether baseline or change in OSA severity was associated with ambulatory BP at 4-year follow-up. METHODS: Children who participated in our previous OSA prevalence research were invited to undergo a repeat overnight sleep study and 24-h ambulatory BP monitoring in this 4-year follow-up study. BP parameters of subjects with differing baseline OSA severity, that is, obstructive apnea-hypopnea index (OAHI) < 1/h, 1 to 5/h, and > 5/h, were compared. Overweight and normal-weight children were analyzed separately. RESULTS: One hundred eighty-five of 306 subjects (60%) were included in the analysis, of whom 58 were overweight at baseline. Linear increasing trends of wake systolic BP (SBP), wake diastolic BP (DBP), and sleep SBP z scores at follow-up were found across groups of increasing baseline OSA severity in the normal weight but not in the overweight subgroup. After adjusting for BMI z score, baseline OAHI was independently associated with all BP z scores at follow-up but not associated with changes in BP z scores across 4 years. On the other hand, change in OAHI was independently associated with sleep SBP and DBP z scores at follow-up and with changes in sleep SBP and DBP z scores across 4 years. CONCLUSIONS: This study provides longitudinal data as additional proof that childhood OSA is associated with elevated BP independent of obesity.

The effect of childhood obstructive sleep apnea on ambulatory blood pressure is modulated by the distribution of respiratory events during rapid eye movement and nonrapid eye movement sleep.

OBJECTIVE: We aimed to investigate if different childhood obstructive sleep apnea (OSA) subtypes, namely rapid eye movement (REM)-related, nonrapid eye movement (NREM)-related and stage-independent OSA would exert different effects on ambulatory blood pressure (ABP). METHODS: Data from our previous school-based cross-sectional study were reanalyzed. Subjects who had an obstructive apnea-hypopnea index (OAHI) between 1 and 10 events per hour and a total REM sleep duration of >30min were included in our analysis. REM-related and NREM-related OSA were defined as a ratio of OAHI in REM sleep (OAHIREM) to OAHI in NREM sleep (OAHINREM) of >2 and <0.5, respectively. The others were classified as stage-independent OSA. RESULTS: A total of 162 subjects were included in the analysis. In the mild OSA (OAHI, 1-5events/h) subgroup, no significant differences in any ABP parameters were found between OSA subtypes. On the other hand, in subjects with moderate OSA (OAHI, 5-10events/h), the REM-related OSA subtype had a significantly lower daytime systolic blood pressure (SBP) z score (-0.13±0.90 cf 1.15±0.67; P=.012) and nighttime SBP z score (0.29±1.06 cf 1.48±0.88, P=.039) than the stage-independent OSA subtype. Linear regression analyses revealed that OAHINREM but not OAHIREM was significantly associated with both daytime (P=.008) and nighttime SBP (P=.042) after controlling for age, gender, and body size. CONCLUSION: Children with obstructive events mainly in REM sleep may have less cardiovascular complications than those with stage-independent OSA.

Natural history of primary snoring in school-aged children: a 4-year follow-up study.

BACKGROUND: The objective of this study was to examine the natural history of childhood primary snoring (PS) and to identify predictive clinical symptoms and risk factors associated with PS progression to obstructive sleep apnea (OSA). METHODS: Children aged 6 to 13 years old who received a diagnosis of PS in our previous community-based OSA prevalence study were invited to undergo repeat polysomnography (PSG) at 4-year follow-up. Subjects with an obstructive apnea hypopnea index (OAHI) ≥ 1 were classified as having OSA at follow-up. RESULTS: Seventy children (60% boys) with a mean age of 14.7 ± 1.8 years were analyzed in this follow-up study. The mean duration of follow-up was 4.6 ± 0.6 years. At follow-up, 26 subjects (37.1%) progressed to OSA, of whom five (7.1%) had moderate to severe disease (OAHI ≥ 5). Twenty-two (31.4%) remained at PS, and 18 (25.7%) had complete resolution of their snoring with normal PSG. Persistent snoring had a positive predictive value of 47.7% and a negative predictive value of 86.4% for progression from PS to OSA. Multivariate logistic regression analysis showed that persistent overweight/obesity was a significant risk factor for the development of OSA at follow-up, with an OR of 7.95 (95% CI, 1.43-44.09). CONCLUSIONS: More than one-third of school-aged children with PS progressed to OSA over a 4-year period, although only 7.1% developed moderate to severe disease. Weight control may be an important component in the management of PS because obesity was found to be a significant risk factor for PS progression.

Does rapid eye movement sleep behavior disorder exist in psychiatric populations? A clinical and polysomnographic case-control study.

OBJECTIVES: Rapid eye movement (REM) sleep behavior disorder (RBD) has been increasingly reported in patients with psychiatric disorders (pRBD). Although a close association with the usage of psychotropics has been postulated, it remains elusive whether psychotropics are the only causative factor of RBD symptoms in psychiatric populations. Moreover, there is limited literature documenting and quantifying the clinical and polysomnographic features in this population. METHODS: A case-control study comparing the clinical and polysomnographic features of 31 pRBD patients with: (1) Age-, sex-, and psychiatric diagnoses-matched controls; and (2) Typical idiopathic RBD (tRBD) patients. RESULTS: Despite being prescribed with similar psychotropics, pRBD patients had more dream-enacting behaviors (p<0.01), sleep-related injuries (p<0.01), and nightmares (p<0.01) than the psychiatric controls. pRBD patients were younger with more females, but they had comparable sleep-related injuries to tRBD. Both tRBD and pRBD had more REM-related muscle activity than controls (p<0.01) and the effect remained significant after adjusting for age, gender, and use of antidepressants. CONCLUSIONS: Our study suggests that pRBD had comparable clinical features and consequences to those of tRBD. The occurrence of RBD symptoms in these patients may be related to a constellation of factors, including individual predisposition, depressive illness, antidepressants, and other clinical factors. Given the association of RBD and neurodegeneration in tRBD, further prospective follow-up of these patients is warranted.

Amelioration of obstructive sleep apnea in REM sleep behavior disorder: implications for the neuromuscular control of OSA.

OBJECTIVES: The relationship between REM sleep behavior disorder (RBD) and obstructive sleep apnea (OSA) remains unclear. We aimed to (1) explore the association of REM-related EMG activity (REMREEA) with OSA in RBD patients; (2) compare the severity of OSA between RBD patients with OSA (RBD-OSA) and their age-, sex-, AHI-, and BMI- matched OSA controls. DESIGN: a. Correlation study in consecutive RBD subjects and b. case-control study SETTING: Sleep laboratory PARTICIPANTS: 71 RBD patients in the correlation study and 55 subjects (28 RBD-OSA cases and 27 OSA controls) in the case-control study. INTERVENTION: N/A METHODS: Polysomnographic assessment to document the sleep architecture, sleep apnea related parameters, and REMREEA. RESULTS: (1) In the correlation study, increased REMREEA was associated with lower severity of OSA in RBD patients, including total AHI (r = -0.263), NREM AHI (r = -0.242), obstructive AHI (r = -0.265), and mean apnea duration (r = -0.353) (P < 0.05). (2) In the case-control study, RBD-OSA patients had lesser severity of sleep apnea parameters than OSA controls in terms of higher nadir SpO(2) (85.7% ± 4.9% vs 80.8% ± 5.9%, P < 0.01), shorter maximum hypopnea duration (53.8 ± 16.7 vs 69.4 ± 22.4 seconds, P < 0.05), and maximum (45.8 ± 20.5 vs 60.8 ± 19.6 sec, P < 0.01) and mean apnea duration (22.3 ± 8.1 vs 26.3 ± 5.8 sec, P < 0.05). Significant interaction effects indicated that the usual REM sleep exacerbation of sleep apneas was seen only in OSA controls but not in RBD subjects. CONCLUSIONS: This study demonstrated that excessive EMG activity in RBD might protect patients against severe OSA and suggests this may be a naturalistic model for understanding neuromuscular control of OSA.

Familial aggregation of narcolepsy.

OBJECTIVES: To determine the familial aggregation of narcolepsy from perspectives of clinical symptomatology, polysomnographic data, and human leukocyte antigen (HLA) typing. METHODS: This was a Family study at the University-affiliated hospital. The participants were narcolepsy probands and their first degree relatives, and, also, age and sex matched unrelated healthy controls. Interventions were not applicable. MEASUREMENTS AND RESULTS: All study subjects underwent structured interviews, overnight polysomnography followed by a multiple sleep latency test (MSLT), and HLA typing. Altogether, 33 probands and 81 first degree relatives (response rate 65%) were recruited. Among the relatives, 12.3% were diagnosed with narcolepsy and 39.5% had narcolepsy spectrum as defined by unexplained abnormal MSLT (shortened MSL and SOREMP) results. The relative risk of narcolepsy in first degree relatives was 361.8. Familial aggregation of narcolepsy symptoms, excessive daytime sleepiness, HLA status, abnormal MSLT, and nocturnal polysomnographic findings were observed. CONCLUSIONS: The familial risk of narcolepsy among first degree relatives is much higher than previously reported. There exists a spectrum of narcolepsy features among relatives, ranging from full clinical tetrads to asymptomatic abnormal MSLT findings.

Parasomnia among psychiatric outpatients: a clinical, epidemiologic, cross-sectional study.

OBJECTIVE: Epidemiologic studies from general population and clinical case series suggest association of parasomnias with mental illnesses and psychotropic medications. This cross-sectional study aimed at determining the prevalence rate of sleepwalking, sleep-related eating disorder (SRED), rapid eye movement sleep behavior-like disorder (RSBD-like disorder), and sleep-related injury (SRI) and their associated factors in an adult psychiatric outpatient clinic. METHOD: Subjects aged 18 to 65 years who were attending an outpatient clinic in Hong Kong from May 2006 through June 2006 were included in this cross-sectional study. A 3-phase design was employed, including a structured questionnaire on parasomnias, followed by clinical interviews of both questionnaire-positive and -negative groups, and polysomnography for subjects having active parasomnias in recent 1 year. In addition, the principal psychiatric diagnoses, medical illnesses, and detailed drug history over recent 1 year were retrieved from the computerized records. RESULTS: Twelve hundred thirty-five subjects completed the phase 1 interview. The estimated prevalence of the lifetime diagnoses of sleepwalking, SRED, SRI, sleep violence, and RSBD-like disorder were 8.5%, 4.0%, 21.0%, 3.6%, and 5.8%, respectively, while the 1-year prevalence of these conditions were 2.9%, 2.4%, 8.8%, 2.5%, and 3.8%, respectively. These conditions were associated with depression and a constellation of sleep disturbances. Specific combinations of psychotropics were found to pose risk in particular parasomnias: sedative antidepressants and nonbenzodiazapine hypnotics in sleepwalking, regular zolpidem and antidepressants in SRED, and selective serotonin reuptake inhibitors in RSBD-like disorder. CONCLUSIONS: Sleepwalking, SRED, RSBD-like disorder, and SRI were common and underrecognized among the psychiatric population in this study. Their occurrences were likely contributed by interacting effect of mental illnesses, sleep disturbances, and specific psychotropic medications. Further prospective study is warranted for clarification of the etiology and clinical management of these potentially dangerous and "hidden" parasomnias.