N2 Sleep Research Articles

Associations Among Sleep Apnea, Objective or Subjective Sleep Duration, and Recurrence of Atrial Fibrillation in Patients Who Undergo Radiofrequency Catheter Ablation for Persistent Atrial Fibrillation - A Prospective Observational Study.

Sleep apnea (SA), subjective sleep duration (SSD), and objective sleep duration (OSD) were reported as risk factors for atrial fibrillation (AF). However, the association between AF and the combination of SA and OSD has not been clarified. Nor has a mismatch between SSD and OSD been investigated. We assessed SA with polysomnography, OSD with actigraphy, and SSD in patients who underwent radiofrequency catheter ablation for persistent AF. We investigated associations among SA, OSD, OSD×3% oxygen desaturation index (3%ODI), and AF recurrence, considering SSD-OSD (i.e., the difference between SSD and OSD) and OSD. Seventy of 94 (74.4%) participants had moderate-to-severe SA (apnea-hypopnea index [AHI] ≥15). Participants were classified into OSD tertiles. Participants in Tertile 3 (mean OSD: 7.3 h) had decreased SSD-OSD (0.0 h) with increased Stage N1 sleep. Over 27.6 months, 10 AF recurrences occurred in 51 participants without treatment for SA. AHI ≥20 and OSD Tertile 3 were associated with AF recurrence (hazard ratios 5.7 [95% confidence interval 1.1-24.7] and 10.3 [95% confidence interval 1.2-88.4], respectively). Participants with AF recurrence had a higher OSD×3%ODI. SA and long OSD were predictors of recurrent AF through long exposure to intermittent hypoxia during sleep. SSD-OSD was low in patients with long OSD, possibly because of decreased sleep quality.

Sleep Characteristics of Patients Admitted to Intensive Care Units after Major Abdominal Surgery

Purpose : The aim of this study was to investigate sleep parameters and architecture in patients admitted to the intensive care unit (ICU) on the day of abdominal surgery. Methods : A total of ten patients who underwent laparotomy under general anesthesia at the hepatopancreatobiliary surgery department of a general hospital in Busan, South Korea participated in this observational study. We measured total sleep time (TST), sleep efficiency (SE), wake after sleep onset (WASO), and sleep stages on their first night in the ICU using the WatchPAT300. Furthermore, we used nonparametric statistics to examine differences in postoperative sleep based on sedative administration. Results : The Median (IQR) TST for the participants was 399.50(263.80) minutes; the SE was 75.1 (30.4)%; the WASO rate was 27.8(30.6)%; and the WASO frequency was 5.50(8.50) times. Patients’ rapid eye movement (REM) sleep time was 114.31(87.88) minutes, with 55.8(11.9)% of N1, 18.2(5.3)% of N2, and 24.8 (11.7)% of N3 sleep stages. The sedation group had a longer TST (Z=-2.619, <i>p</i> =.008), higher SE (Z=-2.611, <i>p</i> =.008), lower WASO rate (Z=-2.611, <i>p</i> =.008), smaller number of WASOs (Z=-2.627, <i>p</i> =.008), and longer REM sleep (Z=-2.617, <i>p</i> =.008) compared to the non-sedation group. Conclusion : We observed a high rate of light sleep and awakenings during sleep in patients admitted to the ICU after surgery. Moreover, non-sedated patients lacked either deep or REM sleep. Sleep-improving interventions are needed for non-sedated surgical patients who are admitted to the ICU.

The evaluation of a novel single-lead biopotential device for home sleep testing.

This paper reports on the clinical evaluation of the sleep staging performance of a novel single-lead biopotential device. 133 patients suspected of obstructive sleep apnea were included in a multi-site cohort. All patients underwent polysomnography and received the study device, a single-lead biopotential measurement device attached to the forehead. Clinical endpoint parameters were selected to evaluate the device's ability to determine sleep stages. Finally, the device's performance was compared to the clinical study results of comparable devices. Concurrent PSG and study device data were successfully acquired for 106 of the 133 included patients. The results of this study demonstrated significant similarity in overall sleep staging performance (5-stage Cohen's Kappa of 0.70) to the best-performing reduced-lead biopotential device to which it was compared (5-stage Cohen's Kappa of 0.73). Contrary to the comparator devices, the study device reported a higher Cohen's Kappa for REM (0.78) compared to N3 (0.61), which can be explained by its particular measuring electrode placement (diagonally across the lateral cross-section of the eye). This placement was optimized to ensure the polarity of rapid eye movements could be adequately captured, enhancing the capacity to discriminate between N3 and REM sleep when using only a single-lead setup. The results of this study demonstrate the feasibility of incorporating a single-lead biopotential extension in a reduced-channel home sleep apnea testing setup. Such incorporation could narrow the gap in the functionality of reduced-channel home sleep testing and in-lab polysomnography without compromising the patient's ease of use and comfort.

Impaired Sleep-Dependent Memory Consolidation in Pediatric Narcolepsy Type 1.

Disrupted nighttime sleep (DNS) is common in pediatric Narcolepsy type 1, yet its cognitive impact is unknown. As N2 sleep spindles are necessary for sleep-dependent memory consolidation, we hypothesized that Narcolepsy Type 1 impairs memory consolidation via N2 sleep fragmentation and N2 sleep spindle alterations. We trained 28 pediatric Narcolepsy Type 1 participants and 27 healthy controls (HC) on a spatial declarative memory task before a nocturnal in-lab polysomnogram and then gave them a cued recall test upon awakening in the morning. We extracted wake and sleep stage bout numbers and N2 spindle characteristics from the polysomnogram and conducted mixed model analysis of sleep-dependent memory consolidation to identify group differences. Narcolepsy Type 1 participants had shorter N2 bout durations and associated shorter N2 spindles vs. HC, but other N2 spindle features were similar. Narcolepsy Type 1 participants had worse memory performance post-sleep than HCs after adjusting for age and gender (mean memory consolidation HC: -3.1% ± 18.7, NT1: -15.6 ± 24.8, main effect group x time of testing F=5.3, p=0.03). We did not find significant relationships between sleep-dependent memory consolidation and N2 spindle characteristics. Notably, increased N1% was associated with worse sleep-dependent memory consolidation with results driven by the Narcolepsy Type 1 group. Sleep-dependent memory consolidation is mildly impaired in youth with Narcolepsy Type 1 and findings may be attributed to increases in N1 sleep. Further studies are needed to determine if these findings are generalizable and reversible with sleep-based therapies.

Sex differences in the risk of excessive daytime sleepiness in mild and moderate ischaemic stroke patients: a retrospective database study

BackgroundExcessive daytime sleepiness (EDS) is a common complication of stroke that has a detrimental effect on patients’ daily life and functional recovery. The clinical characteristics and risk factors for poststroke EDS may differ between males and females.MethodsA retrospective study based on hospital medical records was conducted on patients with a diagnosis of stroke who participated in polysomnographic monitoring at the Affiliated Hospital of Yangzhou University from February 2022 to May 2024. Baseline data, laboratory test data, polysomnographic data, and related scale scores were retrospectively collected. The Epworth Sleepiness Scale (ESS) score was used to assess EDS after stroke. Binary logistic regression was used to determine the risk factors for daytime sleepiness. The study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. Statistical analysis was performed via IBM SPSS 26.0.ResultsESS scores were higher in males than in females, whereas females had higher Pittsburgh Sleep Quality Index (PSQI) scores and Hospital Anxiety and Depression Scale (HADS) scores. Male sex and higher depression scores were risk factors for EDS; among male patients, higher anxiety scores were a risk factor for EDS, whereas smoking was a protective factor. Depression, a higher arousal index and a reduced proportion of N3 sleep periods were risk factors for EDS in females.ConclusionsThe characteristics and influencing factors of EDS differ between the sexes in patients with mild and moderate ischaemic stroke. Our study may provide evidence and guidance for clinical diagnosis and treatment. Interventional studies are needed to assess the impact of treating these risk factors in the future.

Caffeine Intake Alters Recovery Sleep after Sleep Deprivation.

Caffeine is a well-known psychostimulant reputed to alleviate the deleterious effects of sleep deprivation. Nevertheless, caffeine can alter sleep duration and quality, particularly during recovery sleep. We evaluated the effects of acute caffeine intake on the duration and quality of recovery sleep following total sleep deprivation (TSD), taking into account daily caffeine consumption. Forty-one participants performed a double-blind, crossover TSD protocol (38 h of continuous wakefulness) with acute caffeine or placebo. Caffeine (2.5 mg/kg) or placebo was administered twice during continuous wakefulness (last treatment 6.5 h before bedtime for the recovery night). Polysomnographic measurements were recorded using a connected headband. TSD was associated with a rebound in total sleep time (TST) on the recovery night (+110.2 ± 23.2 min, p < 0.001). Caffeine intake decreased this recovery TST (-30.2 ± 8.2 min p = 0.02) and the N3 sleep stage duration (-35.6 ± 23.2 min, p < 0.01). Caffeine intake altered recovery sleep continuity (increased number of long awakenings), stability (higher stage transition frequency), and organization (less time spent in complete sleep cycle) and decreased the delta power spectral density during NREM sleep. On the recovery night, habitual daily caffeine consumption was negatively correlated with TST in caffeine and placebo conditions and positively correlated with wake after sleep onset (WASO) duration and with the frequency of long (>2 min) awakenings in the caffeine condition only. Acute caffeine intake during TSD affects nighttime recovery sleep, with an interaction with daily consumption. These results may influence advice on caffeine intake for night-shift workers. (NCT03859882).

Polysomnographic and clinical characteristics of sleep apnea headache patients.

Sleep apnea headache can be defined as a persistent, widespread, throbbing headache that occurs recurrently, is not accompanied by any additional symptoms after waking up, and usually resolves within four hours. Diagnosis of the condition requires confirmation through polysomnography with an apnea-hypopnea index of at least 5, indicating the presence of obstructive sleep apnea syndrome (OSAS). While sleep apnea headaches are common in 10-15% of individuals with OSAS, morning headaches are experienced by 5% of this population. The aim of this study is to examine both polysomnographic and clinical features associated with sleep apnea headache in individuals confirmed to have OSAS by polysomnography. The study was conducted in the sleep center of University of Health Science, Erenköy Mental and Nervous Disease Training and Research Hospital. We have examined the clinical and polysomnographic data of the patients with sleep apnea headache (SAH) diagnosed according to IHS-3 criteria retrospectively and grouped the patients as mild, moderate and severe OSAS. Patients with morning headache except sleep apnea headache and under PAP titration treatment were excluded. The differences between the sleep macro structures of patients with (WSAH) and without sleep apnea headache (WOSAH) were examined. The WSAH group consisted of 384 participants and the control group (WOSAH) consisted of 294 participants The mean age was 46.29 ± 12.18 and 45.08 ± 12.62 years, respectively. Patients in the WSAH group had significantly higher scores on the Epworth Sleepiness Scale (ESS) (p = 0.004) and higher periodic limb movement index (PLMI) (p = 0.014) compared to the WOSAH group. WSAH patients exhibited shorter wake times after sleep onset (WASO) and lower scores on the sleep quality index, in contrast to WOSAH patients. Additionally, within the WSAH group, there was a negative correlation between age and several sleep parameters, including total sleep parameters. A positive correlation was observed between sleep duration (p = 0.009), waking up after sleep (p = 0.043), sleep efficiency (p = 0.001) and apnea-hypopnea index (AHI) (p = 0.018). Additionally, ESS scores were positively correlated with AHI and total awake time (p = 0.000 and p = 0.008, respectively), while negatively correlated with stage N3 sleep percentage and mean minimum oxygen level (p = 0.001 and p = 0.020, respectively) in the WSAH group. The causes and possible mechanisms of sleep apnea headache are not fully clarified and the underlying processes are not fully understood. Sleep apnea headaches appear to be related to disturbances in nocturnal sleep. Dysregulation in regions that modulate sleep and nociception may be one possible mechanism.

Effect of closed-loop vibration stimulation on sleep quality for poor sleepers.

Recent studies have investigated the autonomic modulation method using closed-loop vibration stimulation (CLVS) as a novel strategy for enhancing sleep quality. This study aimed to explore the effects of CLVS on sleep quality, autonomic regulation, and brain activity in individuals with poor sleep quality. Twenty-seven participants with poor sleep quality (Pittsburgh sleep quality index >5) underwent two experimental sessions using polysomnography and a questionnaire, one with CLVS (STIM) and the other without (SHAM). Sleep macrostructure analysis first showed that CLVS significantly reduced the total time, proportion, and average duration of waking after sleep onset. These beneficial effects were paralleled by significantly increased self-reported sleep quality. Moreover, there was a significant increase in the normalized high-frequency (nHF) and electroencephalography relative powers of delta activity during N3 sleep under STIM. Additionally, coherence analysis between nHF and delta activity revealed strengthened coupling between cortical and cardiac oscillations. This study demonstrated that CLVS significantly improves sleep quality in individuals with poor sleep quality by enhancing both subjective and objective measures. These findings suggest that CLVS has the potential to be a practical, noninvasive tool for enhancing sleep quality in individuals with sleep disturbances, offering an effective alternative to pharmacological treatments.

Temporal Lobe Epilepsy with Bitemporal Interictal Epileptiform Discharges: Effects of Sleep and Wakefulness

Introduction. Independent bitemporal interictal discharges are often found in patients with temporal lobe epilepsy. The likelihood of registering epileptiform activity (EA) is higher during sleep. Assessment of bitemporal interictal epileptiform discharges (BIEDs) with various discharge predominance ratio is used for presurgical evaluation of epilepsy patients and prediction of surgical outcomes. Our objective was to determine the predominant side (PS) in patients with bitemporal epilepsy using the incidence of epileptiform discharges for each sleep stage. Materials and methods. We analyzed 45 recordings of 10–24 h long-term video-EEG monitoring (LTM) in patients with bitemporal EA. For each recording, the total incidence of EA (IEA) and EA incidence for wakefulness and for each sleep stage were calculated individually. We also assessed the discharge predominance index (DPI) as a ratio of IEA in the predominant and contralateral sides for the entire recording and for each sleep stage. Results. We observed an IEA increase with sleep deepening, with maximum values observed during N2 and N3 sleep stages. The minimum IEA values were recorded during REM sleep; nevertheless, most of the REM sleep discharges were detected on the PS. DPI values were the highest and the most stable during N2 and N3 stages. Conclusion. The findings of our study demonstrate an increase in DPI values with non-rapid eye movement (NREM) sleep deepening in patients with bitemporal localization of EA. Despite the protective effects of REM sleep (i.e., reducing the likelihood of EA), it may be pivotal in lateralization of EA in patients with BIEDs. The PS is generally determined by a higher DPI during N2 and N3 stages.

Impact of mini-dose dexmedetomidine supplemented analgesia on sleep structure in patients at high risk of obstructive sleep apnea: a pilot trial.

Obstructive sleep apnea (OSA) is common in surgical patients and associated with worse perioperative outcomes. To investigate the effect of mini-dose dexmedetomidine supplemented analgesia on postoperative sleep quality pattern in patients at high risk of OSA. A pilot randomized, double-blind, placebo-controlled trial. A tertiary university hospital in Beijing, China. One hundred and fifty-two adult patients who had a STOP-Bang score ≥3 and a serum bicarbonate level ≥28 mmol/L and were scheduled for major noncardiac surgery between 29 January 2021 and 20 September 2022. After surgery, patients were provided with high-flow nasal cannula and randomized in a 1:1 ratio to receive self-controlled opioid analgesia supplemented with either mini-dose dexmedetomidine (median 0.02 μg/kg/h) or placebo. We monitored polysomnogram from 9:00 pm to 6:00 am during the first night. Our primary outcome was the percentage of stage 2 non-rapid eye movement (N2) sleep. Secondary and exploratory outcomes included other postoperative sleep structure parameters, sleep-respiratory parameters, and subjective sleep quality (Richards-Campbell Sleep Questionnaire; 0-100 score range, higher score better). All 152 patients were included in intention-to-treat analysis; 123 patients were included in sleep structure analysis. Mini-dose dexmedetomidine supplemented analgesia increased the percentage of stage N2 sleep (median difference, 10%; 95% CI, 1 to 21%; p = 0.029); it also decreased the percentage of stage N1 sleep (median difference, -10%; 95% CI, -20% to -1%; p = 0.042). Other sleep structure and sleep-respiratory parameters did not differ significantly between the two groups. Subjective sleep quality was slightly improved with dexmedetomidine on the night of surgery, but not statistically significant (median difference, 6; 95% CI, 0 to 13; p = 0.060). Adverse events were similar between groups. Among patients at high risk of OSA who underwent noncardiac surgery, mini-dose dexmedetomidine supplemented analgesia may improve sleep quality without increasing adverse events. Clinicaltrials.gov, identifier NCT04608331.

Beyond bedwetting: How successful treatment is observed in sleep macrostructure

IntroductionSleep enuresis (SE), commonly known as bedwetting, refers to involuntary urination during sleep. It is a prevalent condition affecting approximately 15 % of children at age 5, 10 % by age 7, and 5 % by age 10. This condition can significantly impact both children and their families. The pathophysiology of SE is complex and not yet fully understood. There are several established treatment methods, but limited information on their sleep dynamics. ObjectiveThis study aimed to evaluate differences in sleep structure before and after treatment in patients with monosymptomatic SE (MSE), focusing on alarm therapy, desmopressin, and a combination of both. The analysis compared pre- and post-treatment differences within each treatment arm. The analysis was conducted for both successful and unsuccessful treatment outcomes. Methods/resultsThis was a prospective study with MSE patients, aged 6–16 years, diagnosed by multidisciplinary assessment. Of the 140 initial applicants 75 were initially included in the study and randomized for therapeutic intervention in three treatment arms, namely: alarm, desmopressin and alarm + desmopressin. Therapeutic response was evaluated 12 months after treatment discontinuation. Polysomnographic evaluation pre and post treatment was carried out. 51/75 completed the entire protocol. 42/51 were successfully treated and had a median age of 10 [8–12] and the non-success, 8 [7–10]. Among the successful patients, the percentage of N2 sleep decreased from a median of 55.7 %–48.5 % (p = 0.0004) in the alarm arm, from 58.8 % to 50 % (p = 0.002) in the desmopressin arm, and from 54.7 % to 50.9 % (p = 0.044) in the combined arm. The percentage of N3 sleep increased from 25.7 % to 30.1 % (p = 0.004) in the alarm arm, from 21.6 % to 26 % (p = 0.032) in the desmopressin arm, and from 23.7 % to 28.3 % (p = 0.014) in the combined arm. The arousal index significantly increased from pre-to post-treatment in all arms: in the alarm arm, from 1.25 to 2.8 (p = 0.002); in the desmopressin arm, from 1.3 to 2.7 (p = 0.019); and in the combined treatment arm, from 1 to 4 (p = 0.003). No significant differences were observed in the non-successful arm or among those who experienced complete resolution of the enuresis without treatment. ConclusionThe observed increase in N3 sleep and arousal and decrease in N2 sleep following successful treatment, regardless of the specific interventions, underscores the role of sleep in the pathophysiology of enuresis. Conversely, the lack of sleep differences in the non-successful arm further highlights the importance of sleep, beyond developmental factors, in influencing the clinical outcomes of enuresis, especially since all children were assessed 12 months after the start of treatment.

Age-related changes in sleep spindle characteristics in individuals over 75 years of age: a retrospective and comparative study

BackgroundSleep and its architecture are affected and changing through the whole lifespan. We know main modifications of the macro-architecture with a shorter sleep, occurring earlier and being more fragmented. We have been studying sleep micro-architecture through its pathological modification in sleep, psychiatric or neurocognitive disorders whereas we are still unable to say if the sleep micro-architecture of an old and very old person is rather normal, under physiological changes, or a concern for a future disorder to appear. We wanted to evaluate age-related changes in sleep spindle characteristics in individuals over 75 years of age compared with younger individuals.MethodsThis was an exploratory study based on retrospective and comparative laboratory-based polysomnography data registered in the normal care routine for people over 75 years of age compared to people aged 65–74 years. We were studying their sleep spindle characteristics (localization, density, frequency, amplitude, and duration) in the N2 and N3 sleep stages. ANOVA and ANCOVA using age, sex and OSA were applied.ResultsWe included 36 participants aged > 75 years and 57 participants aged between 65 and 74 years. An OSA diagnosis was most common in both groups. Older adults receive more medication to modify their sleep. Spindle localization becomes more central after 75 years of age. Changes in the other sleep spindle characteristics between the N2 and N3 sleep stages and between the slow and fast spindles were conformed to literature data, but age was a relevant modifier only for density and duration.ConclusionWe observed the same sleep spindle characteristics in both age groups except for localization. We built our study on a short sample, and participants were not free of all sleep disorders. We could establish normative values through further studies with larger samples of people without any sleep disorders to understand the modifications in normal aging and pathological conditions and to reveal the predictive biomarker function of sleep spindles.

A spectrum of altered non-rapid eye movement sleep in schizophrenia.

Multiple facets of sleep neurophysiology, including electroencephalography (EEG) metrics such as non-rapid eye movement (NREM) spindles and slow oscillations, are altered in individuals with schizophrenia (SCZ). However, beyond group-level analyses, the extent to which NREM deficits vary among patients is unclear, as are their relationships to other sources of heterogeneity including clinical factors, ageing, cognitive profiles and medication regimens. Using newly collected high-density sleep EEG data on 103 individuals with SCZ and 68 controls, we first sought to replicate our previously reported group-level differences between patients and controls (original N=130) during N2 stage. Then in the combined sample (N=301 including 175 patients), we characterized patient-to-patient variability. We replicated all group-level mean differences and confirmed the high accuracy of our predictive model (AUC=0.93 for diagnosis). Compared to controls, patients showed significantly increased between-individual variability across many (26%) sleep metrics. Although multiple clinical and cognitive factors were associated with NREM metrics, collectively they did not account for much of the general increase in patient-to-patient variability. Medication regimen was a greater contributor to variability. Some sleep metrics including fast spindle density showed exaggerated age-related effects in SCZ, and patients exhibited older predicted biological ages based on the sleep EEG; further, among patients, certain medications exacerbated these effects, in particular olanzapine. Collectively, our results point to a spectrum of N2 sleep deficits among SCZ patients that can be measured objectively and at scale, with relevance to both the etiological heterogeneity of SCZ as well as potential iatrogenic effects of antipsychotic medication.

Exploring Sleep Architecture in Polish Patients with Multiple Sclerosis: A Polysomnography Study.

Sleep disturbances are a prevalent phenomenon in patients with multiple sclerosis (PwMS). The present study employs polysomnography (PSG) to quantify sleep efficiency and architecture in PwMS, aiming to elucidate the relationships between PSG parameters and factors including gender, disability level, brain lesion location, and subjective measures of insomnia, excessive daytime sleepiness (EDS), fatigue, pain, and mood disorders. The study cohort comprised 51 adult PwMS, of whom 31 underwent overnight PSG. The demographic and clinical characteristics, including age, gender, and Expanded Disability Status Scale (EDSS), were collated. The Athens Insomnia Scale, the Epworth Sleepiness Scale, the Fatigue Severity Scale, the Modified Fatigue Impact Scale (MFIS), the Numerical Pain Rating Scale, and the Hospital Anxiety and Depression Scale were employed for the assessment of insomnia, EDS, fatigue, pain, and mood disorders. The brain and spinal cord magnetic resonance imaging (MRI) were evaluated. A reduced sleep efficiency was observed among 30 PwMS (aged 38.9 ± 12.9), with a mean of 80 ± 12%, especially in those with brainstem demyelinating lesions. In those PwMS aberrant sleep onset latency (SOL) and wake after sleep onset were also noted (p < 0.05). The prevalence of sleep fragmentation, as measured by the total arousal index, was greater in male PwMS than in female (p < 0.05). Higher disability according to the EDSS correlated with longer SOL (ρ = 0.48, p < 0.05), and reduced N2 sleep stage correlated with cognitive fatigue according to MFIS (ρ = -0.46, p < 0.05). Age, disease duration, insomnia, EDS, physical fatigue, and mood disorders did not impact PSG parameters. The study demonstrated the disruption of sleep architecture in PwMS, and highlighted the importance of a comprehensive PSG assessment of sleep disturbances in this population.

Increased sighing during sleep as a marker of multiple system atrophy

Parkinson’s disease (PD) and multiple system atrophy (MSA) can be preceded by isolated REM sleep behavior disorder (iRBD). As excessive sighing during wakefulness is a red flag for MSA in individuals with parkinsonism, we measured sighing during slow wave sleep (N3) and REM sleep as potential biomarkers in 73 participants with MSA, 111 with iRBD, 257 with PD, and 115 controls. The number of sighs/hour of N3 (index) was higher in the MSA group than in the other groups. Sighs were rarer in REM sleep than in N3 sleep. A sigh index greater than 3.4/h of N3 was 95% sensitive in discriminating participants with MSA from controls, and a sigh index greater than 0.8 sigh/h of REM sleep was 87% specific in discriminating participants with MSA from controls. MSA participants with (vs. without) sigh were younger, had a lower apnea-hypopnea index (but no more stridor), and had no other difference in motor, autonomic, cognitive, and sensory symptoms. The sigh index could be used for screening for MSA in the millions of middle-aged persons who receive polysomnography for other purposes. Whether sighing in iRBD predicts preferential conversion towards MSA should be measured in a longitudinal study.

The association between slow-wave sleep and choroid plexus calcifications in older adults. Results from the sleep disorders substudy of the Atahualpa Project cohort.

ObjectiveIt has been suggested that choroid plexus calcifications (CPC) may be associated with glymphatic system dysfunction and with disturbed slow-wave (N3) sleep. If this is the case, volumetric analysis of CPC could be used to estimate the functional ability of the glymphatic system. However, data on this association is limited. This study aims to assess the association between percentages of N3 sleep – used as a putative marker of glymphatic system activity – and the volume of CPC in older adults. Patients and methodsCommunity-dwelling individuals aged ≥60 years enrolled in the Atahualpa Project Cohort received head CTs (for automated determinations of CPC volume) and a single-night polysomnography (PSG) for quantification of N3 sleep percentages. Multivariate linear regression and non-parametric models were fitted to assess the association between these variables. ResultsA total of 125 older adults (median age: 65 years; 32 % males) were included. The mean percentage of N3 sleep was 12.4±9.1 %, and the mean volume of CPC was 655±345.3 µL. Non-parametric locally weighted scatterplot smoothing showed that the volume of CPC increased as the percentage of N3 sleep increased, but only when N3 sleep is reduced (up to 12 % of total sleep time). The significance disappeared when PSG parameters were included in the model as well as in participants with normal N3 sleep percentages. ConclusionsStudy results suggest that in the presence of severe reductions in N3 sleep, increased CPC volume may be a manifestation of choroid plexus compensation or adaptation, and not necessarily dysfunction.

Phase-Amplitude Coupling in Theta and Beta Bands: A Potential Electrophysiological Marker for Obstructive Sleep Apnea.

Phase-amplitude coupling (PAC) between the phase of low-frequency signals and the amplitude of high-frequency activities plays many physiological roles and is involved in the pathological processed of various neurological disorders. However, how low-frequency and high-frequency neural oscillations or information synchronization activities change under chronic central hypoxia in OSA patients and whether these changes are closely associated with OSA remains largely unexplored. This study arm to elucidate the long-term consequences of OSA-related oxygen deprivation on central nervous system function. : We screened 521 patients who were clinically suspected of having OSA at our neurology and sleep centers. Through polysomnography (PSG) and other clinical examinations, 103 patients were ultimately included in the study and classified into mild, moderate, and severe OSA groups based on the severity of hypoxia determined by PSG. We utilized the phase-amplitude coupling (PAC) method to analyze the modulation index (MI) trends between different frequency bands during NREM (N1/N2/N3), REM, and wakefulness stages in OSA patients with varying severity levels. We also examined the correlation between the MI index and OSA hypoxia indices. Apart from reduced N2 sleep duration and increased microarousal index, the sleep architecture remained largely unchanged among OSA patients with varying severity levels. Compared to the mild OSA group, patients with moderate and severe OSA exhibited higher MI values of PAC in the low-frequency theta phase and high-frequency beta amplitude in the frontal and occipital regions during N1 sleep and wakefulness. No significant differences in the MI of phase-amplitude coupling were observed during N2/3 and REM sleep. Moreover, the MI of phase-amplitude coupling in theta and beta bands positively correlated with hypoxia-related indices, including the apnea-hypopnea index (AHI) and oxygenation desaturation index (ODI), and the percentage of oxygen saturation below 90% (SaO2<90%). OSA patients demonstrated increased MI values of theta phase and beta amplitude in the frontal and occipital regions during N1 sleep and wakefulness. This suggests that cortical coupling is prevalent and exhibits sleep-stage-specific patterns in OSA. Theta-beta PAC during N1 and wakefulness was positively correlated with hypoxia-related indices, suggesting a potential relationship between these neural oscillations and OSA severity. The present study provides new insights into the relationship between neural oscillations and respiratory hypoxia in OSA patients.

"I know when to stop": Sentinels and counter-strategies against drowsy driving in narcolepsy and idiopathic hypersomnia.

To collect prodromal symptoms experienced by participants with narcolepsy and idiopathic hypersomnia (considered "hypersomnolence experts") prior to drowsy driving and counter-strategies used to maintain alertness. Systematic, face-to-face interview (using a semi-structured questionnaire), including clinical measures, frequency of car accidents/near misses, and symptoms experienced before impending drowsy driving episodes and counter-strategies. Among 61 participants (32 with narcolepsy, 29 with idiopathic hypersomnia; 56 drivers), 61% of drivers had at least one lifetime accident/near miss. They had a higher sleepiness score (14 ± 4 vs. 11 ± 5, P<0.04) than those without an accident/near miss, but no other differences in demographics, driving experience, medical conditions, symptoms, sleep tests, and treatment. All but three participants experienced prodromal symptoms of drowsy driving, which included postural and motor changes (86.9%: axial hypotonia - e.g., eyelid droop, stereotyped movements), cognitive impairment (53.3%: automatic steering, difficulty concentrating/shifting, dissociation, mind wandering, dreaming), sensory (65%: paresthesia, pain, stiffness, heaviness, blunted perceptions such as a flat dashboard with loss of 3D, illusions and hallucinations), and autonomic symptoms (10%, altered heart/breath rate, penile erection). Counterstrategies included self-stimulation from external sources (pain, cold air, music, drinks, driving with bare feet), motor changes (upright posture, movements), and surprise (sudden braking). Drowsy driving symptoms can result from "local" NREM, entry in N1 sleep, and hybrid wake/REM sleep states. These rich qualitative insights from participants with narcolepsy and idiopathic hypersomnia, as well as sophisticated counter-strategies, can be gathered to reduce the crash risk in this population, but also in inexperienced healthy drivers.

Weight Status, Autonomic Function, and Systemic Inflammation in Children with Obstructive Sleep Apnea.

Children with obstructive sleep apnea (OSA) frequently experience chronic low-grade systemic inflammation, with the inflammasome playing a central role in OSA. This cross-sectional study evaluated the relationship between weight status, autonomic function, and systemic inflammation in a cohort of 55 children with OSA, predominantly boys (78%) with an average age of 7.4 ± 2.2 years and an apnea-hypopnea index of 14.12 ± 17.05 events/hour. Measurements were taken of body mass index (BMI), sleep heart-rate variability, morning circulatory levels of interleukin-1β, interleukin-1 receptor antagonist, and interleukin-6, and tumor necrosis factor-α, anthropometry, and polysomnography. Multiple linear regression modeling showed that an apnea-hypopnea index was significantly associated with BMI, the standard deviation of successive differences between normal-to-normal intervals during N3 sleep, and the proportion of normal-to-normal interval pairs differing by more than 50 ms during rapid-eye-movement sleep. A moderated mediation model revealed that interleukin-1 receptor antagonist levels mediated the association between BMI and interleukin-6 levels, with sympathovagal balance during N3 sleep and minimum blood oxygen saturation further moderating these relationships. This study highlights the complex relationships between BMI, polysomnographic parameters, sleep heart-rate-variability metrics, and inflammatory markers in children with OSA, underlining the importance of weight management in this context.

Construction and validation of clinical prediction model of tongue base collapse under drug-induced sleep endoscopy in OSA patients

Objective: To analyze the correlation between drug-induced sleep endoscopy (DISE), results, polysomnography (PSG) indicators, and clinical parameters in patients with obstructive sleep apnea (OSA), and to establish and validate a predictive model for tongue base plane obstruction. Methods: This retrospective study analyzed 117 OSA patients diagnosed via PSG and treated at the Department of Otolaryngology-Head and Neck Surgery, Nanfang Hospital, Southern Medical University, between October 2014 and March 2022. The cohort comprised of 114 males and 3 females, with an age range of 20 to 54 years (mean age 38.1±8.4 years). Data on DISE results, PSG results, and clinical indicators were collected for all 117 patients. Logistic regression analysis was performed to identify relevant indicators, and a predictive model for tongue base plane obstruction was constructed and internally validated using the R programming language. Results: Univariate logistic regression analysis identified four independent risk factors for predicting tongue root plane obstruction: tonsil grading, N2, N3, and rapid eye movement sleep(REM) stage [OR:0.412(0.260~0.652),1.045(1.012~1.079),0.943(0.903~0.984),0.961(0.925~0.998),P <0.05]. Multivariate logistic regression analysis confirmed tonsil grading and N3 sleep stage (12.48±12.22%) as significant predictors. A nomogram model incorporating these factors demonstrated good predictive performance, with an area under curve(AUC) of 0.82 (95%CI: 0.548-1.000), an optimal cutoff of 0.519, a specificity of 80.0%, and a sensitivity of 86.7%. Internal validation of the model in the validation cohort yielded an AUC of 0.751 (95%CI: 0.625-0.876). Conclusions: Tongue base plane obstruction observed during DISE in OSA patients is associated with tonsil grading and N3 sleep stage duration. The predictive model developed for tongue base plane obstruction based on DISE demonstrates good efficacy, as evidenced by its internal validation.