Distinct effects of orexin receptor antagonist and GABAA agonist on sleep and physical/cognitive functions after forced awakening.

The majority of patients with insomnia are treated with hypnotic agents. In the present study, we evaluated the side-effect profile of an orexin receptor antagonist and γ-aminobutyric acid A (GABAA) receptor agonist on physical/cognitive functions upon forced awakening. This double-blind, randomized, placebo-controlled, cross-over study was conducted on 30 healthy male subjects. Fifteen minutes before bedtime, the subjects took a pill of suvorexant (20 mg), brotizolam (0.25 mg), or placebo and were forced awake 90 min thereafter. Physical- and cognitive-function tests were performed before taking the pill, after forced awakening, and the next morning. Polysomnographic recordings revealed that the efficacies of the hypnotic agents in prolonging total sleep time (∼30 min) and increasing sleep efficiency (∼6%) were comparable. When the subjects were allowed to go back to sleep after the forced awakening, the sleep latency was shorter under the influence of hypnotic agents (∼2 min) compared to the placebo trial (24 min), and the rapid eye movement latency was significantly shorter under suvorexant (98.8, 81.7, and 48.8 min for placebo, brotizolam, and suvorexant, respectively). Although brotizolam significantly impaired the overall physical/cognitive performance (sum of z score) compared with placebo upon forced awakening, there was no significant difference in the total z score of performance between suvorexant and placebo. Notably, the score for static balance with the eyes open was higher under suvorexant compared to brotizolam administration. The energy expenditure was lower under suvorexant and brotizolam compared with the placebo. The effect size of brotizolam (d = 0.24) to reduce the energy expenditure was larger than that of suvorexant (d < 0.01).

Clinical, polysomnographic, and cephalometric features of obstructive sleep apnea with AHI over 100.

PURPOSE: Obstructive sleep apnea (OSA) is induced by a sleep-related collapse of the upper airway in association with multiple factors. The severity of OSA is determined by the apnea-hypopnea index (AHI). Although obesity and sex differences are common factors in OSA, the level of the AHI varies to the same degree according to the age and sex and degree of obesity. However, only a few studies have evaluated AHI over 100/h, those reports did not describe why they set the AHI cutoff at 100/h. The purpose of this study was to elucidate the pathogenesis of "very" severe OSA, defined as having an AHI > 100/h. METHODS: AHI > 100/h was set as very severe OSA (VS-OSA) in this study. As controls, moderate to severe OSA patients, matched with VS-OSA for age, sex, and body mass index (BMI), were enrolled. The findings of polysomnography and cephalography between VS-OSA and controls were compared. RESULTS: Eleven patients in the VS-OSA group (mean AHI 110.2/h) and 22 patients in the control group (mean AHI 41.6/h) were compared (mean age 50.2 vs 50.6, male:female 5:6 vs 10:12, mean BMI 35.4 kg/m2 vs 34.5 kg/m2). There were no significant differences in the clinical characteristics. In the polysomnographic parameters, the VS-OSA group showed apnea predominance, the mean percutaneous oxygen saturation (SO2) was significantly lower in all sleep stages, and the minimum SO2 was significantly lower (49.0% vs 77.5%, p = 0.002). A similar apnea duration and rather shorter hypopnea duration were shown. The time of apnea-to-arousal was significantly earlier (- 0.1 s vs 0.9 s, p = 0.003). Lung-to-finger circulation time showed no differences. The cephalometric findings showed no significant differences. CONCLUSIONS: VS-OSA patients were more likely to have apnea predominance, desaturation when sleeping despite a similar apnea duration, and rather shorter hypopnea duration, and arousals were evoked significantly earlier.

Prevalence of Restless Legs Syndrome and Its Effects on Sleep and Health-Related Quality of Life in Patients With Heart Failure.

BACKGROUND: Restless legs syndrome (RLS) is a neurological disorder characterized by leg restlessness and dysesthesia. Although the relationship between RLS and heart failure (HF) has been reported, the prevalence and clinical significance of RLS in patients with HF remain to be elucidated. METHODS AND RESULTS: We enrolled consecutive patients with HF who were admitted to our institutions. RLS was diagnosed using the International Restless Legs Syndrome Study Group criteria. Subjective sleepiness, sleep quality, and quality of life (QoL) were assessed using the Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and 8-item Short Form (SF-8), respectively. Among the 133 patients, 18 (13.6%) had RLS and were younger than those without RLS (62.4±13.4 vs 70.0±12.2, P = .017). The RLS group had significantly disrupted sleep quality and QoL, with greater PSQI score (8.0±3.2 vs 5.9±3.3, P = .015) and lower SF-8 physical component summary (PCS) score (35.6±6.5 vs 40.7±9.5, P = .031), despite similar ESS and SF-8 mental component summary scores. In the multivariable regression analysis, RLS was associated with greater PSQI (ß=0.211; P = .014) and lower PCS score (ß=-0.177; P = .045). CONCLUSION: In the patients with HF, RLS was prevalent, and sleep quality and QoL may be disrupted by RLS.

Association between patterns of jaw motor activity during sleep and clinical signs and symptoms of sleep bruxism.

The aim of this study was to investigate the association between patterns of jaw motor activity during sleep and clinical signs and symptoms of sleep bruxism. A total of 35 university students and staff members participated in this study after providing informed consent. All participants were divided into either a sleep bruxism group (n = 21) or a control group (n = 14), based on the following clinical diagnostic criteria: (1) reports of tooth-grinding sounds for at least two nights a week during the preceding 6 months by their sleep partner; (2) presence of tooth attrition with exposed dentin; (3) reports of morning masticatory muscle fatigue or tenderness; and (4) presence of masseter muscle hypertrophy. Video-polysomnography was performed in the sleep laboratory for two nights. Sleep bruxism episodes were measured using masseter electromyography, visually inspected and then categorized into phasic or tonic episodes. Phasic episodes were categorized further into episodes with or without grinding sounds as evaluated by audio signals. Sleep bruxism subjects with reported grinding sounds had a significantly higher total number of phasic episodes with grinding sounds than subjects without reported grinding sounds or controls (Kruskal-Wallis/Steel-Dwass tests; P < 0.05). Similarly, sleep bruxism subjects with tooth attrition exhibited significantly longer phasic burst durations than those without or controls (Kruskal-Wallis/Steel-Dwass tests; P < 0.05). Furthermore, sleep bruxism subjects with morning masticatory muscle fatigue or tenderness exhibited significantly longer tonic burst durations than those without or controls (Kruskal-Wallis/Steel-Dwass tests; P < 0.05). These results suggest that each clinical sign and symptom of sleep bruxism represents different aspects of jaw motor activity during sleep.

Effect of clonazepam and clonidine on primary sleep bruxism: a double-blind, crossover, placebo-controlled trial.

The aim of this study was to assess the acute effects of clonazepam and clonidine on rhythmic masticatory muscle activity in young adults with primary sleep bruxism, as well as accompanying effects on sleep architecture and cardiac activity. This study used a double-blind, crossover, placebo-controlled design. Polysomnography was performed on 19 subjects [nine men and 10 women; mean age (±SE): 25.4 ± 2.7 years] for 5 nights. The first 2 nights were used for the habituation and diagnosis of sleep bruxism. The other 3 nights were randomly assigned for clonazepam (1.0 mg), clonidine (0.15 mg) or placebo (all administered 30 min before bedtime). Sleep, oromotor activity and cardiac activity variables were assessed and compared among the three drug conditions. Clonidine significantly reduced the median percentage of time spent in the rapid eye movement sleep stage compared with placebo and clonazepam. The number of rhythmic masticatory muscle activity episodes was reduced with clonidine by >30% compared with placebo and clonazepam. The reduction of rhythmic masticatory muscle activity index by clonidine was associated with an increase of mean RR intervals (slower heart rate) during quiet sleep periods and during a 70-s period before the onset of rhythmic masticatory muscle activity episodes. However, no changes in cardiac activity variables were observed for clonazepam. In young adults with primary sleep bruxism, clonidine was significantly more effective in suppressing sleep bruxism than clonazepam. The acute effects of clonidine on rhythmic masticatory muscle activity episodes may be mediated by suppression of autonomic nervous system activity and non-rapid eye movement-rapid eye movement sleep processes.

Impact on Clinical Outcomes of Periodic Leg Movements During Sleep in Hospitalized Patients Following Acute Decompensated Heart Failure.

BACKGROUND: Periodic leg movements during sleep (PLM) are characterized by regularly recurring movement of the legs during sleep. Although PLM is common and a predictor of death in patients with chronic heart failure, the clinical significance of PLM in hospitalized patients with a reduced left ventricular ejection fraction (LVEF) following acute decompensated heart failure (ADHF) remains unknown.Methods and Results:After initial improvement of acute signs and symptoms of ADHF, 94 consecutive patients with reduced LVEF who underwent polysomnography were enrolled. They were divided into 2 groups based on the presence or absence of severe PLM defined as PLM index ≥30. The risks for clinical events, composite of all-cause death and rehospitalization, were assessed using a stepwise multivariable Cox proportional model including variables showing P<0.10 in univariate analyses. Severe PLM was observed in 21 patients (22%). At a median follow-up of 5.2 months, 30 patients experienced clinical events (32%). In the multivariable analysis, the presence of severe PLM was significantly associated with increasing clinical events (hazard ratio, 2.16; 95% confidence interval, 1.03-4.54; P=0.042) independent of hemoglobin level and the severity of sleep-disordered breathing. CONCLUSIONS: In hospitalized patients with systolic dysfunction following ADHF, severe PLM was prevalent and significantly associated with increased risk of death and/or rehospitalization.

Bradyarrhythmias may induce central sleep apnea in a patient with obstructive sleep apnea.

The relationship between central sleep apnea (CSA) and bradyarrhythmia remains unclear. We report the case of a 70-year-old man with severe obstructive sleep apnea and bradyarrhythmia due to sick sinus syndrome in whom concomitant CSA was alleviated after pacemaker implantation.

Craniofacial anatomical risk factors in men with obstructive sleep apnea and heart failure: a pilot study.

PURPOSE: Obstructive sleep apnea (OSA) is complicated with heart failure (HF); however, the reason for this is not well understood. Craniofacial anatomic risk factors may contribute to OSA pathogenesis in HF patients. However, there are no data about cephalometric findings among OSA patients with HF. METHODS: Consecutive patients with HF and OSA (defined as total apnea-hypopnea index (AHI) ≥15/h) were enrolled. As controls, OSA patients without HF but matching the test group in age, BMI, and obstructive AHI were also enrolled. RESULTS: Overall, 17 OSA patients with HF and 34 OSA patients without HF were compared. There are no significant differences in the characteristics or polysomnographic parameters between 2 groups. In the cephalometric findings, compared with patients without HF, patients with HF showed a significantly greater angle between the line SN to point "A" (SNA) and a longer inferior airway space and greater airway area. However, the tongue area of patients with HF was more than those without HF. CONCLUSIONS: The craniofacial structures of OSA patients with HF were different from those without HF. OSA patients with HF had an upper airway anatomy that is more likely to collapse when sleeping while recumbent, despite having a larger airway space.

Phasic jaw motor episodes in healthy subjects with or without clinical signs and symptoms of sleep bruxism: a pilot study.

BACKGROUND: To investigate the association between each clinical diagnosis criterion for sleep bruxism (SB) and the frequency of jaw motor events during sleep. METHODS: Video-polysomnography was performed on 17 healthy adult subjects (mean age, 26.7 ± 2.8 years), with at least one of the following clinical signs and symptoms of SB: (1) a report of frequent tooth grinding, (2) tooth attrition with dentine exposure through at least three occlusal surfaces, (3) morning masticatory muscle symptoms, and (4) masseter muscle hypertrophy. Episodes of rhythmic masticatory muscle activity (RMMA) and isolated tonic activity were scored visually. These variables were compared with regards to the presence or absence of each clinical sign and symptom. RESULTS: In 17 subjects, 4.0 ± 2.5/h (0.1-10.2) RMMA and 1.0 ± 0.8/h (0-2.4) isolated tonic episodes were observed (total episodes: 5.0 ± 2.4/h (1.2-11.6)). Subjects with self-reported grinding sounds (n=7) exhibited significantly higher numbers of RMMA episodes (5.7 ± 2.3/h) than those without (n=10; 2.8 ± 1.8/h) (p=0.011). Similarly, subjects with tooth attrition (n=6) showed significantly higher number of RMMA episodes (5.6 ± 3.1/h) than those without (n=11; 3.2 ± 1.6/h) (p=0.049). The occurrence of RMMA did not differ between the presence and absence of morning masticatory muscle symptoms or muscle hypertrophy. CONCLUSIONS: Clinical signs and symptoms frequently used for diagnosing SB can represent different clinical and physiological aspects of jaw motor activity during sleep.

A handmade eye movement monitor using a piezoelectric device during transsphenoidal surgery.

We describe a handmade eye movement monitor featuring a piezoelectric device for use during transsphenoidal surgery (TSS). The sensor consists of a piezoelectric device, condensers, resistors, and several inexpensive parts. Eyeball movements elicited by surgical manipulations during TSS for cavernous sinus tumor are detected by small disc-shaped sensors taped to the eyelids. The responses could be monitored as sharp waves on an electroencephalograph. After we started using this monitor, both the incidence and the severity of cranial nerve injuries during TSS for cavernous sinus tumor decreased. Our device is especially useful at operations to remove functioning pituitary adenomas invading the cavernous sinus and contributes to their favorable endocrine outcomes. None of our patients manifested the postoperative swelling of the eyelids or conjunctival congestion generally seen in patients subjected to the insertion of needle sensors for the acquisition of electromyograms of the extraocular muscles, which is widely used during surgery to identify the cranial nerves responsible for eye movement. Our monitor is less expensive and easier to use than any commercially available sensor devices. As our method does not require the insertion of needle sensors, it is less invasive than electromyography of the extraocular muscles.

Changes in the Objective Measures of Sleep in Association with Menses Among Female Athletes with Poor Subjective Sleep Quality: Female Athletes with Poor Subjective Sleep Quality Have More Sleep Arousals During Menses.

Purpose: Female athletes with menstrual abnormalities have poor sleep quality. However, whether female athletes with poor sleep quality based on subjective assessment have distinctive changes in objective measures of sleep in association with menses remains unclear. This study aimed to compare changes in objective sleep measurements during and following menses between collegiate female athletes with and without poor subjective sleep quality. Patients and Methods: Female collegiate athletes (age range/mean ± standard deviation: 18-22/ 22.2±1.1) with regular menstrual cycles were recruited. The participants underwent home electroencephalogram monitoring during the first and second nights after the onset of menses and one night between the seventh and 10th nights after menses onset (mid-follicular phase). The Pittsburgh Sleep Quality Index (PSQI) was used to assess the subjective sleep quality. Interactions between the presence of poor subjective sleep quality (ie, PSQI ≥6) and changes in objective measures of sleep in association with menses were analyzed. Results: Data of 45 athletes, including 13 with poor subjective sleep quality, showed that changes in arousal index in athletes with poor subjective sleep quality were distinctive from those in athletes without poor subjective sleep quality (p = 0.036 for interaction). In athletes with poor subjective sleep quality, the arousal index was significantly increased in menses (p for analysis of variance, 0.015), especially on the first night after the onset of menses compared with during the mid-follicular phase (p = 0.016). Conclusion: Collegiate female athletes with regular menstrual cycles are likely to have poor subjective sleep quality in association with more frequent arousal during the first night after the onset of menses than during the mid-follicular phase.

Orexin receptor antagonist increases fat oxidation and suppresses protein catabolism during sleep in humans.

Suvorexant is an orexin receptor antagonist that targets the wake-promoting system. Orexin is also known to regulate energy metabolism in rodents, but its role in humans remains largely unknown. Here, we assessed the effect of suvorexant (20 mg) on energy metabolism during sleep and shortly after awakening in a randomized, double-blind, placebo-controlled, crossover study in 14 healthy men. Suvorexant increased rapid eye movement (REM) but decreased nonrapid eye movement (NREM) stage 1. Energy expenditure during wake after sleep onset (WASO) was higher than that during NREM and REM sleep in the placebo but not in the suvorexant trial, suggesting that the increase in energy expenditure during WASO was due to an activation of the orexin system. Fat oxidation during sleep increased, and its effect remained after waking the next morning. Suvorexant decreased protein catabolism but did not affect overall energy expenditure. The orexin system may affect fat oxidation independent of its roles in sleep regulation in humans.

A case of middle-aged central sleep apnea due to Joubert syndrome with different treatment effects of oxygen and acetazolamide.

We report a case of severe central sleep apnea incidentally diagnosed during polysomnography for suspected obstructive sleep apnea. Characteristic clinical features included episodic hyperventilation followed by apnea from hypocapnia, which did not follow a Cheyne-Stokes pattern. Combined with the identification of cerebellar and brainstem malformations known as the "molar tooth sign" on a brain MRI, developmental delay, and motor coordination problems, Joubert syndrome (a congenital disease) was first diagnosed at the age of 50 years. Central apneas were also observed during wakefulness, although not continuously. During sleep, continuous positive airway pressure and adaptive servo-ventilation were ineffective at the referring clinic and at our hospital. Supplemental oxygen decreased the frequency of central apneas and significantly shortened the duration of each central sleep apnea compared with room air. In contrast, the opposite response was observed with acetazolamide administration.

Validation of sleep-staging accuracy for an in-home sleep electroencephalography device compared with simultaneous polysomnography in patients with obstructive sleep apnea.

Efforts to simplify standard polysomnography (PSG) in laboratories, especially for obstructive sleep apnea (OSA), and assess its agreement with portable electroencephalogram (EEG) devices are limited. We aimed to evaluate the agreement between a portable EEG device and type I PSG in patients with OSA and examine the EEG-based arousal index's ability to estimate apnea severity. We enrolled 77 Japanese patients with OSA who underwent simultaneous type I PSG and portable EEG monitoring. Combining pulse rate, oxygen saturation (SpO2), and EEG improved sleep staging accuracy. Bland-Altman plots, paired t-tests, and receiver operating characteristics curves were used to assess agreement and screening accuracy. Significant small biases were observed for total sleep time, sleep latency, awakening after falling asleep, sleep efficiency, N1, N2, and N3 rates, arousal index, and apnea indexes. All variables showed > 95% agreement in the Bland-Altman analysis, with interclass correlation coefficients of 0.761-0.982, indicating high inter-instrument validity. The EEG-based arousal index demonstrated sufficient power for screening AHI ≥ 15 and ≥ 30 and yielded promising results in predicting apnea severity. Portable EEG device showed strong agreement with type I PSG in patients with OSA. These suggest that patients with OSA may assess their condition at home.

Impact of sleep-disordered breathing on overnight changes in arterial stiffness in patients with acute heart failure.

Overnight increases in arterial stiffness associated with sleep-disordered breathing may adversely affect patients with acute heart failure. Thus, we investigated overnight changes in arterial stiffness and their association with sleep-disordered breathing in patients hospitalized for acute heart failure. Consecutive patients with acute heart failure were enrolled. All participants underwent overnight full polysomnography following the initial improvement of acute signs and symptoms of acute heart failure. The arterial stiffness parameter, cardio-ankle vascular index (CAVI), was assessed before and after polysomnography. Overall, 60 patients (86.7% men) were analyzed. CAVI significantly increased overnight (from 8.4 ± 1.6 at night to 9.1 ± 1.7 in the morning, P < 0.001) in addition to systolic and diastolic blood pressure (from 114.1 mmHg to 121.6 mmHg, P < 0.001; and from 70.1 mmHg to 78.2 mmHg, P < 0.001, respectively). Overnight increase in CAVI (ΔCAVI ≥ 0) was observed in 42 patients (70%). The ΔCAVI ≥ 0 group was likely to have moderate-to-severe sleep-disordered breathing (i.e., apnea-hypopnea index ≥15, 55.6% vs 80.9%, P = 0.047) and greater obstructive respiratory events (29.4% vs 58.5%, P = 0.041). In multivariable analysis, moderate-to-severe sleep-disordered breathing and greater obstructive respiratory events were independently correlated with an overnight increase in CAVI (P = 0.033 and P = 0.042, respectively). In patients hospitalized for acute heart failure, arterial stiffness, as assessed by CAVI, significantly increased overnight. Moderate-to-severe sleep-disordered breathing and obstructive respiratory events may play an important role in the overnight increase in cardio-ankle vascular index.

Relationship between atrial conduction delay and obstructive sleep apnea.

Prolonged P-wave duration, indicating atrial conduction delay, is a marker of left atrial abnormality and is reported as a potent precursor of atrial fibrillation (AF). Several studies have shown that obstructive sleep apnea (OSA) is associated with AF. We evaluated the relationship between OSA and prolonged P-wave duration. Consecutive subjects who underwent overnight polysomnography and showed a normal sinus rhythm, had no history of AF or ischemic heart disease, and showed no evidence of heart failure were enrolled. Apnea-hypopnea index (AHI) is defined as the number of apnea and hypopnea events per hour of sleep. P-wave duration was determined on the basis of the mean duration of three consecutive beats in lead II from a digitally stored electrocardiogram. A total of 250 subjects (middle-aged, predominantly male, mildly obese, with a mean P-wave duration of 106 ms) were enrolled. In addition to age, male gender, body mass index (BMI), hypertension, dyslipidemia, and uric acid and creatinine levels, AHI (r = 0.56; P < 0.001) had significant univariable relationship with P-wave duration. Multivariate regression analysis showed that age, BMI, male gender, and AHI (partial correlation coefficient, 0.47; P < 0.001) were significantly independently correlated to P-wave duration. Severity of OSA is significantly associated with delayed atrial conduction time. Obstructive sleep apnea may lead to progression of atrial remodeling as an AF substrate.

Diagnostic accuracy of ambulatory polysomnography with electroencephalogram for detection of sleep bruxism-related masticatory muscle activity.

STUDY OBJECTIVES: This study investigated the diagnostic accuracy of Sleep Profiler, which relies on ambulatory polysomnography (PSG) with electroencephalogram for sleep bruxism (SB) and examined its episode-by-episode agreement in comparison to PSG equipped with audiovisual recordings (avPSG). METHODS: This prospective 2-gate study recruited 10 individuals with probable SB and 10 healthy volunteers. Overnight experimental recordings were performed simultaneously using the ambulatory PSG with masseter electromyography and avPSG with masseter and temporalis electromyography. Sleep staging was performed manually for avPSG and automatically or manually for ambulatory PSG. SB episodes were manually scored based on electromyography signals with reference to sleep stages. The episode-by-episode agreement was analyzed by setting avPSG as the reference standard. The sensitivity, specificity, and accuracy for the diagnosis of SB were calculated after optimizing the cutoff values of the episode index and the burst index. RESULTS: Regarding the episode-by-episode agreement, median sensitivities were 0.825 and positive predictive values were approximately 0.6, regardless of the sleep staging procedure, indicating that approximately 40% of the overall total SB episodes scored by the ambulatory PSG were false positives. Because of overestimation of SB episodes, the optimal cutoff values for the episode index and the burst index were approximately 1.5 times higher than the avPSG-based cutoff values and dramatically improved the diagnostic precision metrics for the ambulatory PSG. CONCLUSIONS: Sleep Profiler can eliminate events during wakefulness by electroencephalogram and may provide a definitive diagnosis in patients with possible SB by applying optimized cutoff values. However, the risk of overestimation must be recognized. CLINICAL TRIAL REGISTRATION: Registry: UMIN Clinical Trials Registry; Name: Accuracy of Portable PSG Device for Detection of Sleep Bruxism-Related Masseter EMG Muscle Activity; URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000037380; Identifier: UMIN000032793. CITATION: Abe Y, Nakazato Y, Takaba M, Kawana F, Baba K, Kato T. Diagnostic accuracy of ambulatory polysomnography with electroencephalogram for detection of sleep bruxism-related masticatory muscle activity. J Clin Sleep Med. 2023;19(2):379-392.

Cross-Sectional Relationship Between Atrial Conduction Delay and Arterial Stiffness in Patients with Obstructive Sleep Apnea.

Aim: Prolonged P-wave duration (PWD), which indicates atrial conduction delay, is a potent precursor of atrial fibrillation (AF) that may be induced by obstructive sleep apnea (OSA). The cardio-ankle vascular index (CAVI), which is an arterial stiffness parameter, is elevated in patients with OSA; moreover, an increased CAVI is associated with atrial conduction delay through left atrium enlargement in association with left ventricular diastolic dysfunction. We aimed to examine the relationship between the CAVI and PWD in patients with OSA. Methods: We included patients with a sinus rhythm who underwent overnight polysomnography. We measured the PWD and CAVI on standard 12-lead electrocardiograms; further, we analyzed the relationship between PWD and CAVI. Results: We analyzed data from 300 participants (men, 89.0%; mean age, 52.3 ± 13.1 years; and body mass index, 26.2 ± 3.9 kg/m2). The mean PWD was 104.4 ± 10.4 ms while the mean CAVI was 7.5 ± 1.5. PWD was significantly correlated with CAVI (r = 0.478, p < 0.001); additionally, PWD and CAVI were directly associated with OSA severity (p = 0.002 and p = 0.002, respectively). Multivariate regression analysis revealed an independent significant correlation of PWD and CAVI with OSA severity. Conclusion: In patients with OSA, an increase in arterial stiffness is associated with atrial conduction delay.

Impact of radiotherapy for head and neck cancer on obstructive sleep apnea: a prospective study.

BACKGROUND: In recent years, a relatively high prevalence of obstructive sleep apnea (OSA) in patients following radiotherapy (RT) for head and neck cancer (HNC) has been reported; however, little is known regarding the impact of RT on sleep disorders and the underlying mechanisms. This aim of this study was to elucidate the pathogenesis of OSA by comparing the clinical and sleep test parameters and magnetic resonance imaging (MRI) findings before and after HNC treatment with radiation. METHODS: This prospective study included patients scheduled for RT with or without chemotherapy or bioradiotherapy for HNC. Patients diagnosed with HNC between May 2017 and August 2020 were consecutively recruited. The results of the sleep tests were analyzed both before and after treatment. The clinical characteristics of the patients and cephalometric and MRI parameters were also measured. RESULTS: First, a total of 32 patients (64.8±11.8 years old; BMI, 22.7±3.6 kg/m2) underwent pre-treatment sleep tests. The prevalence of OSA [apnea hypopnea index (AHI) ≥5] in these patients was 81.3% (26 patients) before treatment, and the mean AHI was 20.8±19.0 events/hr. Next, 21 patients performed a sleep test both before and after treatment. Regarding subjective symptoms, there were no significant differences in the Epworth Sleepiness Scale (ESS) (P=0.142) or Pittsburgh Sleep Quality Index (PSQI) (P=0.935) after treatment; however, the BMI and neck circumference significantly decreased after treatment (P<0.0001 and P=0.0001, respectively). The incidence of OSA in these patients was 81.0% (17 patients) before treatment and 85.7% (19 patients) after treatment (P=1.0). Overall, the AHI was not significantly different, changing only from 14.5 to 14.9 after treatment (P=0.147). The MRI parameters showed that the retroglossal pharyngeal area increased significantly after treatment (P=0.007). CONCLUSIONS: This study found that the prevalence of OSA before and after RT for HNC was higher than that in the normal population, despite a significant decrease in BMI and increase in the retroglossal pharyngeal area after treatment. We suggest that physicians who manage patients with HNC should consider the occurrence of OSA before and after treatment.

Automated sleep stage scoring employing a reasoning mechanism and evaluation of its explainability.

Scoring sleep stages from biological signals is an essential but labor-intensive inspection for sleep diagnosis. The existing automated scoring methods have achieved high accuracy but are not widely applied in clinical practice. In our understanding, the existing methods have failed to establish the trust of sleep experts (e.g., physicians and clinical technologists) due to a lack of ability to explain the evidences/clues for scoring. In this study, we developed a deep-learning-based scoring model with a reasoning mechanism called class activation mapping (CAM) to solve this problem. This mechanism explicitly shows which portions of the signals support our model's sleep stage decision, and we verified that these portions overlap with the "characteristic waves," which are evidences/clues used in the manual scoring process. In exchange for the acquisition of explainability, employing CAM makes it difficult to follow some scoring rules. Although we concerned the negative effect of CAM on the scoring accuracy, we have found that the impact is limited. The evaluation experiment shows that the proposed model achieved a scoring accuracy of [Formula: see text]. It is superior to those of some existing methods and the inter-rater reliability among the sleep experts. These results suggest that Sleep-CAM achieved both explainability and required scoring accuracy for practical usage.