Sleep Arousal Research Articles

Sleep arousal detection for monitoring of sleep disorders using one-dimensional convolutional neural network-based U-Net and bio-signals

PurposeSleep arousal detection is an important factor to monitor the sleep disorder.Design/methodology/approachThus, a unique nth layer one-dimensional (1D) convolutional neural network-based U-Net model for automatic sleep arousal identification has been proposed.FindingsThe proposed method has achieved area under the precision–recall curve performance score of 0.498 and area under the receiver operating characteristics performance score of 0.946.Originality/valueNo other researchers have suggested U-Net-based detection of sleep arousal.Research limitations/implicationsFrom the experimental results, it has been found that U-Net performs better accuracy as compared to the state-of-the-art methods.Practical implicationsSleep arousal detection is an important factor to monitor the sleep disorder. Objective of the work is to detect the sleep arousal using different physiological channels of human body.Social implicationsIt will help in improving mental health by monitoring a person's sleep.

MSleepNet: A Semi-Supervision-Based Multiview Hybrid Neural Network for Simultaneous Sleep Arousal and Sleep Stage Detection

MSleepNet: A Semi-Supervision-Based Multiview Hybrid Neural Network for Simultaneous Sleep Arousal and Sleep Stage Detection

Sleep disruption due to nocturnal heartburn: a review of the evidence and clinical implications

Nocturnal heartburn (NHB) is a symptom that affects up to 25% of the general population and has been shown to cause sleep disruption that adversely affects quality of life and psychomotor performance. Few studies have evaluated the association between occasional NHB and sleep disturbances; therefore, this connection may be underappreciated and left untreated by the primary care provider and patient, with potentially significant negative clinical consequences and effects on quality of life. This review sought to describe what is currently known about the interplay between occasional NHB and sleep disruption, and identify whether acid suppression therapy can improve symptoms of occasional NHB and associated sleep disruptions. The pathophysiology of heartburn-induced sleep disruption appears to follow a bidirectional cycle due to the normal physiologic changes that occur in the upper gastrointestinal tract during sleep and due to the potential for heartburn symptoms to cause sleep arousal. The majority of the identified studies suggested that pharmacologic interventions for acid reduction, including proton pump inhibitors or histamine type-2 receptor antagonists (H2RAs), improved objective and/or subjective sleep outcomes among individuals with gastroesophageal reflux disease (GERD) and NHB. Several studies specific to famotidine demonstrated that treatment with 10 mg or 20 mg reduced nighttime awakenings due to NHB. In conclusion, NHB symptoms can cause sleep dysfunction that can have a profound adverse downstream effect on quality of life, next-day functioning, and health-related outcomes. The current approach to managing occasional NHB is similar to that associated with GERD, highlighting the need for studies specific to the occasional heartburn population. Health care providers should investigate NHB as one of the potential causes of sleep complaints, and patients with heartburn should be questioned about sleep quality, recalled arousals, next-day vitality, early fatigue, and next-day functioning.

Respiratory event index underestimates severity of sleep apnea compared to apnea-hypopnea index.

Polygraphy (PG) is often used to diagnose obstructive sleep apnea (OSA). However, it does not use electroencephalography, and therefore cannot estimate sleep time or score arousals and related hypopneas. Consequently, the PG-derived respiratory event index (REI) differs from the polysomnography (PSG)-derived apnea-hypopnea index (AHI). In this study, we comprehensively analyzed the differences between AHI and REI. Conventional AHI and REI were calculated based on total sleep time (TST) and total analyzed time (TAT), respectively, from two different PSG datasets (n = 1561). Moreover, TAT-based AHI (AHITAT) and TST-based REI (REITST) were calculated. These indices were compared keeping AHI as the gold standard. The REI, AHITAT, and REITST were significantly lower than AHI (p < 0.0001, p ≤ 0.002, and p ≤ 0.01, respectively). The total classification accuracy of OSA severity based on REI was 42.1% and 72.8% for two datasets. Based on AHITAT, the accuracies were 68.4% and 85.9%, and based on REITST, they were 65.9% and 88.5% compared to AHI. AHI was most correlated with REITST (r = 0.98 and r = 0.99 for the datasets) and least with REI (r = 0.92 and r = 0.97). Compared to AHI, REI had the largest mean absolute errors (13.9 and 6.7) and REITST the lowest (5.9 and 1.9). REI had the lowest sensitivities (42.1% and 72.8%) and specificities (80.7% and 90.9%) in both datasets. Based on these present results, REI underestimates AHI. Furthermore, these results indicate that arousal-related hypopneas are an important measure for accurately classifying OSA severity.

Sleep bruxism and associated physiological events in children with obstructive sleep apnea: a polysomnographic study.

The aim of this study was to evaluate the physiological events associated with sleep bruxism (Sleep Bruxism [SB]; presence of mandibular movement activity) and the control window (4 minutes prior to SB event, where no mandibular movement activity was detected) in a polysomnography study in children with mild sleep apnea. Polysomnography data from children aged 4 to 9 years old diagnosed with mild sleep apnea were analyzed by 2 trained examiners. The mandibular movement activity (bruxism event; SB) was classified into phasic and tonic. The control window was selected 4 minutes prior to the SB event. All physiological events were recorded in both bruxism and control windows, including sleep phase (N1, N2, N3, and rapid eye movement), arousal, leg movements, tachycardia, bradycardia, oxygen desaturation, and number of obstructive and central sleep apnea events. The moment in which those phenomena occurred when associated with SB was also analyzed (before/after). Data were analyzed using 95% confidence intervals (α = 5%). A total of 661 mandibular movements were analyzed and classified as tonic (n = 372) or phasic (n = 289). The mean apnea-hypopnea index was 1.99 (SD = 1.27) events/h. The frequency of leg movements, microarousal, and tachycardia was increased in SB events when compared with the control window (P < .05). There was an increase in bradycardia frequency in the control window when compared with SB (in both tonic and phasic events). The frequency of obstructive and central apnea during SB was lower when compared with the other physiological phenomena. There is a difference in the physiological parameters evaluated in children with mild sleep apnea when comparing the 2 windows (SB and control). Sleep bruxism is associated with other physiological phenomena, such as leg movements, tachycardia, and microarousal. The use of a control window (where no mandibular activity was detected) was representative since it did not show activation of the sympathetic nervous system. Bonacina CF, Soster LMSFA, Bueno C, etal. Sleep bruxism and associated physiological events in children with obstructive sleep apnea: a polysomnographic study. J Clin Sleep Med. 2024;20(4):565-573.

Sleep-EEG in comorbid pain and insomnia: implications for the treatment of pain disorders.

Patients with chronic pain experience a high prevalence of comorbid insomnia, which is associated with functional impairment. Recent advances in sleep electroencephalography (sleep-EEG) may clarify the mechanisms that link sleep and chronic pain. In this clinical update, we outline current advancements in sleep-EEG assessments for pain and provide research recommendations. Promising preliminary work suggests that sleep-EEG spectral bands, particularly beta, gamma, alpha, and delta power, may create candidate neurophysiological signatures of pain, and macro-architectural parameters (e.g., total sleep time, arousals, and sleep continuity) may facilitate EEG-derived sleep phenotyping and may enable future stratification in the treatment of pain. Integration of measures obtained through sleep-EEG represent feasible and scalable approaches that could be adopted in the future. We provide research recommendations to progress the field towards a deeper understanding of their utility and potential future applications in clinical practice.

Pharmacological and Non-Pharmacological Management of Obstructive Sleep Apnea

Obstructive sleep apnea (O.S.A.), also referred to as obstructive sleep hypopnea – is a sleep disorder that involvescessation or significant decrease in airflow in the presence of breathing effort. It is the most common type of sleep-disorderedbreathing. It is characterized by episodes of total or partial airway collapse and decreased oxygen saturation or sleep arousal. Asa result of this disturbance, sleep is interrupted and non-restorative. It significantly raises morbidity and mortality in both developedand developing countries. This review aims to review relevant studies on obstructive sleep apnea. The method used is acomputerized search method, the pathophysiology, clinical presentation, complications, diagnostic procedures, and therapeuticchoices from the literature. The effects of O.S.A. on cardiovascular health, mental disease, quality of life, and driving safety aresevere. This course of action highlights the interprofessional team's involvement in treating obstructive sleep apnea, itspathophysiology, and its causes.

O027 Patterns of nocturnal swallow frequency and related tachycardia with sleep stages and obstructive sleep apnoea severity

Abstract Background Swallowing is a complex activity associated with cortical arousal and tachycardia in sleep(1). Obstructive sleep apnoea (OSA) has been associated with dysfunction and altered biomechanics of swallow (2-3). This study seeks to investigate patterns of swallow frequency and associated tachycardia in relation to OSA severity. Methods Anthropometric and polysomnographic data for 70 subjects were analysed. Swallow index (SI; swallows per hour) and average heart rate changes from 30 seconds pre- to 10 seconds post-swallow were derived from epiglottic pressure and electrocardiogram signals respectively. This study had approval from the local district ethics committee. Progress to date Analysis has been completed for 34 subjects (median age 47.5, range 24-64; 24 males), most with at least moderate OSA (n=20/26). Mean SI was 3.2 in subjects without OSA (n=2), 8 in mild OSA (n=4), 5.8 in moderate OSA (n=10) and 9 in severe OSA (n=10). Mean swallow-related tachycardia was 24.3bpm in subjects without OSA, compared to 14.0bpm in those with severe OSA. Mean swallow-related tachycardia increased with progressive sleep stages (14.8bpm in wakefulness; 16.8bpm Stage 1; 16.8bpm Stage 2; 19.0bpm Stage 3; 19.4bpm in REM). A negative correlation was observed between sleep SI and magnitude of associated tachycardia (Pearson correlation r=-0.387, p=0.026). Intended outcome and impact Our results support existing observations that swallow-associated tachycardia is reliably conserved in sleep, and suggest possible new relationships between swallow frequency and associated tachycardia with OSA severity and sleep stage. We intend with further dataset analyses to explore relationships between sleep swallow physiology and OSA pathophysiology.

O025 Sleep outcomes in paediatric patients pre- and post-pharyngoplasty

Abstract Background Pharyngoplasty surgery is undertaken to correct velopharyngeal insufficiency (VPI). The resultant narrowing of the pharyngeal airway can cause obstructive sleep apnoea (OSA), but limited data is available regarding the incidence or severity of this problem. This study will evaluate the effect of pharyngoplasty on the development of OSA in children. Methods We are undertaking a retrospective audit of medical records for children who underwent both polysomnography (PSG) and pharyngoplasty at a tertiary paediatric centre between January 2013 and December 2022. Data from children who underwent PSG and pharyngoplasty will be evaluated and separated according to the timing pre- or post-pharyngoplasty. Analyses will determine the effect of pharyngoplasty on the development and or progression of sleep disordered breathing. Results 176 paediatric patients underwent pharyngoplasty procedures from January 2013-December 2022, including 73 (41%) who also underwent PSG. Full PSG data are available for analysis including sleep staging, arousal, respiratory and gas exchange. Primary outcome will be the obstructive apnoea-hypopnoea index (OAHI), but additional impacts on total apnoea-hypopnea index (AHI), oxygen saturation, CO2, and arousals will also be evaluated. Not all children had studies before and after their surgery so statistical comparison will be made between parameters measured before and after pharyngoplasty, using both paired (where available) and unpaired (for the entire group) testing as appropriate. Intended outcome/impact: This study will evaluate the impact of pharyngoplasty on children’s breathing during sleep. The results will assist in determining the indications for, and appropriate timing for PSG in children undergoing pharyngoplasty procedures for VPI.

Sleep architecture and vitamin D in hypertensives with obstructive sleep apnea: A polysomnographic study.

Obstructive sleep apnea (OSA) and arterial hypertension (AH) are closely linked disorders with common pathophysiological features. The present study aimed to investigate the relationship between AH and OSA by examining sleep architecture, vitamin D concentration and electrolyte levels in patients with these coexisting conditions. A total of 133 patients suspected of having OSA were recruited for examination. The participants were divided into 2 groups: hypertensives (n = 52); and normotensives (n = 81). One full-night polysomnographic examinations were conducted, followed by the statistical analysis of the collected data. Hypertensive individuals displayed increased apnea-hypopnea index (AHI), oxygen desaturation index (ODI), respiratory arousal index (RAI), and periodic limb movement index (PLMI) as compared to non-hypertensive individuals. Moreover, sleep efficiency (SE), the bruxism arousal index (BAI) and oxygen saturation (SpO2)level were decreased in the hypertensive group. In terms of biochemical parameters, hypertensive individuals exhibited a lower magnesium (Mg) level, and higher levels of C-reactive protein (CRP), uric acid (UA) and glucose. Notably, there were no statistical differences in vitamin D concentration between hypertensive and normotensive individuals. The study explored the potential influence of calcium (Ca), Mg, vitamin D, and UA concentrations on the sleep architecture of patients with comorbid AH and OSA. The findings revealed several notable associations. Firstly, sleep fragmentation correlated with Ca level, suggesting a potential role for both Ca and vitamin D in sleep arousals. Secondly, a higher UA concentration was linked to a higher AHI and increased sleep fragmentation. Additionally, alterations in Mg concentration were observed among hypertensive individuals with OSA. However, further research is needed to fully comprehend the potential impact of these factors on the sleep architecture of hypertensive individuals with apnea.

End-to end decision support system for sleep apnea detection and Apnea-Hypopnea Index calculation using hybrid feature vector and Machine learning

Sleep apnea is a disease that occurs due to the decrease in oxygen saturation in the blood and directly affects people's lives. Detection of sleep apnea is crucial for assessing sleep quality. It is also an important parameter in the diagnosis of various other diseases (diabetes, chronic kidney disease, depression, and cardiological diseases). Recent studies show that detection of sleep apnea can be done via signal processing, especially EEG and ECG signals. However, the detection accuracy needs to be improved. In this paper, a ML model is used for the detection of sleep apnea using 19 static sensor data and 2 dynamic data (Sleep score and Arousal). The sensor data is recorded as a discrete signal and the sleep process is divided into 4.8 M segments. In this work, 19 different sensor data sets were recorded with polysomnography (PSG). These data sets have been used to perform sleep scoring. Then, arousal status marking is done. Model training was carried out with the feature vector consisting of 21 data obtained. Tests were performed with eight different machine learning techniques on a unique dataset consisting of 113 patients. After all, it was automatically determined whether people were diseased (a kind of apnea) or healthy. The proposed model had an average accuracy of 97.27%, while the recall, precision, and f-score values were 99.18%, 95.32%, and 97.20%, respectively. After all, the model that less feature engineering, less complex classification model, higher dataset usage, and higher classification performance has been revealed.

Insomnia and REM sleep instability.

In this narrative review, we give an overview of the concept of rapid eye movement sleep instability and its reported implications in the context of insomnia. The term rapid eye movement sleep instability was coined to describe the observation of a modified rapid eye movement quality in insomnia, characterized by an increased tendency of perceiving rapid eye movement sleep as wake, a small but consistent rapid eye movement sleep reduction and an increased rapid eye movement sleep arousal index. Current research highlights relationships that are transdiagnostic in nature, corresponding to the known interaction of insomnia with many psychiatric disorders, and showing relationships to chronic stress and anxiety disorders.

Bright light therapy and early morning attention, mathematical performance, electroencephalography and brain connectivity in adolescents with morning sleepiness.

Adolescents typically sleep too little and feel drowsy during morning classes. We assessed whether morning use of an LED bright light device could increase alertness in school students. Twenty-six (8M/18F) healthy, unmedicated participants, ages 13-18 years, (mean 17.1±1.4) were recruited following screenings to exclude psychopathology. Baseline assessments were made of actigraph-assessed sleep, attention, math solving ability, electroencephalography and structural and functional MRI (N = 10-11, pre-post). Participants nonrandomly received 3-4 weeks of bright light therapy (BLT) for 30 minutes each morning and used blue light blocking glasses for 2 hours before bedtime. BLT devices were modified to surreptitiously record degree of use so that the hypothesis tested was whether there was a significant relationship between degree of use and outcome. They were used 57±18% (range 23%-90%) of recommended time. There was a significant association between degree of use and: (1) increased beta spectral power in frontal EEG leads (primary measure); (2) greater post-test improvement in math performance and reduction in errors of omission on attention test; (3) reduced day-to-day variability in bed times, sleep onset, and sleep duration during school days; (4) increased dentate gyrus volume and (5) enhanced frontal connectivity with temporal, occipital and cerebellar regions during Go/No-Go task performance. BLT was associated with improvement in sleep cycle consistency, arousal, attention and functional connectivity, but not sleep onset or duration (primary measures). Although this was an open study, it suggests that use of bright morning light and blue light blocking glasses before bed may benefit adolescents experiencing daytime sleepiness. Clinical trial registration: Clinicaltrials.gov ID-NCT05383690.

The States of Different 5-HT Receptors Located in the Dorsal Raphe Nucleus Are Crucial for Regulating the Awakening During General Anesthesia.

General anesthesia is widely used in various clinical practices due to its ability to cause loss of consciousness. However, the exact mechanism of anesthesia-induced unconsciousness remains unclear. It is generally thought that arousal-related brain nuclei are involved. 5-Hydroxytryptamine (5-HT) is closely associated with sleep arousal. Here, we explore the role of the 5-HT system in anesthetic awakening through pharmacological interventions and optogenetic techniques. Our data showed that exogenous administration of 5-hydroxytryptophan (5-HTP) and optogenetic activation of 5-HT neurons in the dorsal raphe nucleus (DR) could significantly shorten the emergence time of sevoflurane anesthesia in mice, suggesting that regulation of the 5-HT system using both endogenous and exogenous approaches could mediate delayed emergence. In addition, we first discovered that the different 5-HT receptors located in the DR, known as 5-HT autoreceptors, are essential for the regulation of general anesthetic awakening, with 5-HT1A and 5-HT2A/C receptors playing a regulatory role. These results can provide a reliable theoretical basis as well as potential targets for clinical intervention to prevent delayed emergence and some postoperative risks.

Real-Time Detection of Sleep Arousals with a Head-Mounted Accelerometer.

Wearable electroencephalography (EEG) enables real-time interactions with the sleeping brain in real-life settings. An important parameter to monitor during these interactions are sleep arousals, i.e. temporary increases in EEG frequency, that compose sleep dynamics, but are challenging to detect without delay. We describe the development of an EEG- and accelerometer(ACC)-based sensing approach to detect arousals in real-time. We investigated the ability of these sensing modalities to timely and accurately detect arousals. When evaluated on 6 nights of mobile recordings, ACC had a median real-time delay of 2 s and was therefore better suited for an early detection of arousals than EEG (4.7 s). The detection performance was independent of sleep stages, but worked better on longer arousals. Our results demonstrate that a head-mounted ACC might be a cost-effective and easy-to-integrate solution for arousal detection where short delays are important or EEG signals are not available.

Assessment of emotional stress among patients suffering from obstructive sleep apnea: A cross-sectional study

ABSTRACT Background: Obstructive sleep apnea (OSA) is a sleep disorder in which the upper airway is partially or completely blocked during sleep. As a result, sleep arousal and arterial oxygen saturation are reduced. According to the epidemiological survey, OAS is relatively common among people that may be associated with psychiatric illnesses. Objectives: The primary objective was to evaluate the stress level among patients suffering from OSA. The secondary objective was to compare the gender preference for stress among patients suffering from OSA. Materials and Methods: A cross-sectional study, approved by the Institutional Ethics Committee, was performed to assess emotional stress among patients suffering from OSA. The study involved 20 participants diagnosed with OSA and reported to the Respiratory Department. The stress levels of the study participants were evaluated with a validated, Perceived Stress Scale (PSS) questionnaire given by the American Sociological Association (ASA). Result: The stress levels presented by the study participants showed that 40% (n = 8) subjects had moderate stress and 60% (n = 12) had severe stress and 30.3% of females depicted emotional stress and 26.2% of males for the same. Conclusion: There is a high psychological stress level among patients suffering from OSA. The females had higher predictions when compared to males. Such patients should be offered an intervention program aimed at stress management to enhance their quality of life.

The clinical characteristics of Parkinson's disease patients with concomitant periodic limb movements in sleep

The current study aimed to investigate the clinical characteristics of Parkinson's disease (PD) patients with concomitant periodic limb movements in sleep (PLMS). The clinical data of 36 PD patients who underwent polysomnography (PSG) in Beijing Tiantan Hospital from October 2018 to July 2022 were collected. Unified Parkinson's Disease Rating Scale 3.0 and Hoehn & Yahr (H-Y) stage were used to evaluate the disease severity. Patients were divided into two groups: the PLMS+group periodic limb movements in sleep index [(PLMSI)≥15 times/h] and the PLMS-group (PLMSI<15 times/h), using the PLMSI 15 times/h as the cut-off value. The clinical characteristics between the two groups were compared. There were 15 patients (42%) in the PLMS+group and 21 patients (58%) in the PLMS-group, among which 12 patients (12/15) in the PLMS+group and 9 patients (42.9%) in the PLMS-group had rapid eye movement sleep behavior disorder (RBD). The rate of RBD in PLMS+group was higher than that in PLMS-group (P<0.05). There was statistically significant difference in the blood folate level between the PLMS-group and PLMS+group [6.20 (5.14, 11.70) ng/ml vs 4.41 (3.07, 5.64) ng/ml] (P<0.01). Folate deficiency was more common in the PLMS+group, while no statistically significant differences were found in homocysteine and ferritin levels (both P>0.05). Four patients in the PLMS+group had falling experience, while 14.3% (3/21) patients in the PLMS-group had falling experience. Patients in the PLMS+group were more likely to fall. The PLMS+group had higher arousal index according to PSG [PLMS-group: 11.90 (9.10, 15.80) times/h; PLMS+group: 21.50 (19.35, 29.90) times/h] (P<0.05). No statistically significant differences in other sleep parameters were detected between the two groups (all P>0.05). Meanwhile, the apnea-hypopnea index (AHI) in both groups was higher than normal (<5 times/h), of which the PLMS-group was 9.80 (4.70, 22.20) times/h and the PLMS+group was 8.20 (1.70, 11.15) times/h, indicating that PD patients were more likely to experience sleep apnea and hypopnea. PD patients with PLMS had lower folate level, higher risk for falls, higher sleep arousal index, more sleep fragmentation, and higher prevalence of RBD.

0769 Multidimensional Sleep Health in Adolescents from the General Population: Definition, Thresholds and Construct Validity

Abstract Introduction The RU-SATED model – regularity, satisfaction, alertness, timing, efficiency, and duration – captures the 24-hour experience of sleep to asses multidimensional sleep health (MSH). However, most prior evidence comes from middle-aged adults. We provide updated MSH data in adolescents by leveraging objective and self-reported sleep measures. Methods We studied 377 adolescents (16.4±2.3 yr; 46.4% female; 21.5% racial/ethnic minority) from the Penn State Child Cohort, a randomly-selected population-based sample. Each MSH domain was categorized as “good” or “poor” using cut-offs informed by prior studies and expert consensus. Good cut-offs, assigned a score of 1, that were derived from actigraphy-measured data included: the standard deviation of sleep midpoint ≤1-h (RU), mean of sleep midpoint 2:00-4:00 (T), mean value of sleep efficiency ≥85% (E), and mean total sleep time ≥7.5-h (D). Good cut-offs derived from self-reported rating scales included the absence of insomnia symptoms (S) or excessive daytime sleepiness (A). Values considered poor based on these cut-offs were assigned a score of 0. Scores were summed across all domains to obtain a composite score ranging from 0 to 6, with higher scores indicating better MSH. Morningness and Tanner staging were self-reported, while Sleep and Arousal clusters scores on the Pediatric Behavior Scale were parent-reported. Results The mean composite score was 3.03 ± 1.30 and domains A and D were most commonly rated as poor (64.5% and 65.3%, respectively). Younger age (r=-0.13, p&amp;lt; 0.05) and identifying as non-Hispanic white (r=-0.14, p&amp;lt; 0.01) were significantly associated with higher MSH scores, while sex (r=-0.04, p=0.40), Tanner staging (r=-0.06, p=0.29) or BMI percentile (r=-0.07, p=0.15) were not. Greater morningness (r=-0.29, p&amp;lt; 0.01), less disturbed sleep (r=-0.28, p&amp;lt; 0.01) and higher arousal (r=-0.21, p&amp;lt; 0.01) scores were associated with higher MSH scores. Conclusion Our data-driven approach can be used to assess MSH in the adolescent population. Our definition captures previously identified health disparities in MSH in adults and shows optimal construct validity against self-reports of circadian preference and parent observations of adolescents’ degree of sleep disturbance and arousal. Improving sleep duration and daytime alertness appear to continue to be the most relevant domains impacting overall MSH in adolescents. Support (if any) NIH (R01HL136587,UL1TR000127)

0547 Phenotyping of Obstructive Sleep Apnea and its Difference in mortality

Abstract Introduction Obstructive sleep apnea (OSA), which is associated with a high mortality, is a heterogeneous disease that is affected by various pathophysiology. Although the severity of OSA is divided based on apnea-hypopnea index (AHI), AHI alone did not sufficiently represent these pathologies. The objective of this study is to categorize OSA using PSG data and compare the characteristics of each group including mortality. Methods 7,247 subjects were recruited at the Center for Sleep and Chronobiology, Seoul National University Hospital from June 2004 to December 2021. Demographic data, polysomnography, Sleep scale including Epworth sleepiness scale, Pittsburgh sleep quality index, Beck depression inventory, and Beck anxiety inventory were performed. After categorizing OSA using K-mean cluster analysis, Kaplan-Meir survival analysis and Cox proportional hazard regression analysis were used to evaluate all-cause mortality and hazard ratios. Results Three clusters were identified; Cluster 1 was associated with moderate OSA (mean AHI=19.28/h), high sleep efficiency and low arousal, Cluster 2 with moderate OSA (mean AHI=24.81/h), low sleep efficiency and high arousal, Cluster 3 with the most severe OSA (mean AHI=64.76/h), obese, and decreased O2 saturation. Conventional classification of OSA showed no difference in mortality between group, whereas Cluster 1 and Cluster 3 showed significant higher all-cause mortality compared to not-OSA group (Cluster 1, Log rank p=0.008; Cluster 3 Log rank p&amp;lt; 0.001). The risk of mortality was also significantly increased in cluster 1 (HR 2.048, 95% CI 1.265-3.317, p=0.004) and cluster 3 (HR 3.686, 95% CI 1.871-7.262, p&amp;lt; 0.001). These results were also observed after adjustment for sex, age, BMI and comorbid disease (Cluster 1, HR 2.053, 95% CI 1.197-3.518, p=0.009; Cluster 4, HR 2.640, 95% CI 1.230-5.666, p=0.012). Conclusion Phenotyping of OSA considered multiple variables is more appropriate to predict mortality than conventional classification based on AHI. In addition to evaluate patient with severe OSA, patients with moderate OSA who shows relatively good sleep and low arousal should be cautiously evaluated and monitored. Support (if any) This study was supported by the Technology Innovation Infrastructure program through the Korea Institute for Advancement of Technology funded by the Ministry of Trade, Industry and Energy.(study no.: P0014279, 20009210, Dr. Yu Jin Lee)

Establishment of a chronic insomnia rat model of sleep fragmentation using unstable platforms surrounded by water.

Chronic fragmented sleep is a very common type of insomnia that affects the daily lives of numerous people around the world. However, its pathogenesis is not very clear and a corresponding rat model has not been reported for this purpose at present. The present study aimed to establish a rat model of chronic insomnia with sleep fragmentation using self-made multiple strings of unstable platforms surrounded by shallow water. During the establishment of the models, changes in body weight and differences in food and water intake in the daytime and at night were acquired. The rat models were assessed using several tests, including the Morris water maze test, pentobarbital sodium-induced sleep, infrared monitoring and electroencephalogram/electromyography during sleep. The expression levels of certain inflammatory factors and orexin A were detected in the serum and brain tissues using ELISAs, immunohistochemistry and immunofluorescence. The expression levels of orexin 1 receptor (orexin 1r) were also detected in the brain. Polysomnography indicated that the model rats were successfully prepared with reduced non-rapid eye movement (non-REM) sleep in the daytime, which was increased at night, and considerably lower REM duration during the day and night. The number of instances of sleep arousals were also increased in the day and at night, and the average duration of each sleep bout was decreased in the daytime. The body weights of the model rats increased at a normal rate. However, the reduction of body weight in the daytime and increased in body weight at night were significantly less than those of the control rats. The daytime food and water consumption of the model rats increased significantly compared with that of the control rats, but was similar to that of the control group at night. The Morris water maze test indicated that the model rats were slow to learn to escape the platforms and performed a lower number of target crossings. The pentobarbital-induced sleep experiment confirmed that the model rats exhibited a longer sleep latency and shorter sleep time. The serum IL-1β, IL-6, TNF-α and orexin A levels of the model rats were significantly increased, whereas their serum IL-10 levels were significantly decreased compared with those of the control rats. The expression levels of IL-1β, IL-6, orexin A and orexin 1r in the brain tissues of the model rats were also significantly increased. In conclusion, these data indicate that learning and memory function, sleep time, arousal times, diurnal and nocturnal body weight changes, food and water intake, and expression levels of the specific inflammatory factors orexin A and orexin 1r were altered in the model rats. This suggests the chronic insomnia rat model with sleep fragmentation was successfully established using multiple strings of unstable platforms surrounded by water.