Sleep Stages Research Articles

Fiber intake is inversely associated with the prevalence of circadian syndrome among adults attending NHANES 2005-2016

It is well-known that many modern lifestyles, including the use of artificial light, shift work, irregular or short sleep, sedentary activity, and unhealthy diet can disrupt the circadian rhythm. This disruption can result in the so-called Circadian Syndrome (CircS) which has been identified as a risk factor for a variety of chronic diseases. The concept of Circadian Syndrome (CircS) was first proposed by Zimmet et al in 2019. CircS has been shown to be a better predictor for cardiovascular diseases (CVD) than the metabolic syndrome (MetS) in adults in China and USA 1,2. Dietary patterns are found to be associated with CircS 3, whereby western dietary pattern was positively related, while prudent pattern was inversely associated, with CircS in the US adults. However, no prior study has investigated the association between fiber intake and CircS. We, thus, aimed to fill this research gap. We analysed data from 10,486 adults aged 20 years and above years who attended the 2005-2016 National Health and Nutrition Examination Survey (NHANES). Fiber and other nutrients intake were assessed using two days 24 hours recall. CircS was derived from all five components of MetS (i.e. central obesity, elevated fasting glucose, elevated triglyceride, reduced HDL-Cholesterol and elevated blood pressure), in addition to short sleep (sleep duration <6 hours/day) and depressive symptoms (PHQ-9 score ≥5). A cut-off for CircS was set as ≥ 4 components. Multivariable logistic regression was used to assess the association between fiber intake and CircS. Mean age of participants was 50.3(SD 17.6) years, and 41.3% had CircS. The mean (SD) fiber intake was 7.8 (2.1), 12.9 (1.3), 17.9 (1.7), and 28.9 (8.2) g/day across the quartiles of fiber intake. The prevalence of CircS decreased across quartiles of fiber intake (44.5% in Q4 and 37.1% in Q1). In the multivariable logistic model adjusting for age, gender, ethnicity, energy intake, education and lifestyle factors, across the quartiles of fiber intake, the odds ratios (ORs) (95%CI) for CircS were: 1.00, 0.91 (0.76-1.08), 0.82 (0.70-0.96), 0.79 (0.63-0.98) (p trend 0.012), respectively. No significant interactions were found between fiber intake and race, gender, smoking, alcohol drinking, and physical activity, in relation to CircS. In conclusion, a high fiber intake was associated with a lower prevalence of CircS among US adults. The findings highlight the importance of fiber intake for the prevention of metabolic and circadian syndrome, suggesting a potentially accessible and cost-effective lifestyle approach to improve public health. Our results underscore the concern that most of the US adults had fiber intake below the recommended level. Longitudinal studies are needed to validate the findings in different populations.

Association of Disrupted Delta Wave Activity During Sleep With Long-Term Cardiovascular Disease and Mortality

BackgroundDelta wave activity is a prominent feature of deep sleep, which is significantly associated with sleep quality. ObjectivesThe authors hypothesized that delta wave activity disruption during sleep could predict long-term cardiovascular disease (CVD) and CVD mortality risk. MethodsThe authors used a comprehensive power spectral entropy-based method to assess delta wave activity during sleep based on overnight polysomnograms in 4,058 participants in the SHHS (Sleep Heart Health Study) and 2,193 participants in the MrOS (Osteoporotic Fractures in Men Study) Sleep study. ResultsDuring 11.0 ± 2.8 years of follow-up in SHHS, 729 participants had incident CVD and 192 participants died due to CVD. During 15.5 ± 4.4 years of follow-up in MrOS, 547 participants had incident CVD, and 391 died due to CVD. In multivariable Cox regression models, lower delta wave entropy during sleep was associated with higher risk of coronary heart disease (SHHS: HR: 1.46; 95% CI: 1.02-2.06; P = 0.03; MrOS: HR: 1.79; 95% CI: 1.17-2.73; P < 0.01), CVD (SHHS: HR: 1.60; 95% CI: 1.21-2.11; P < 0.01; MrOS: HR: 1.43; 95% CI: 1.00-2.05; P = 0.05), and CVD mortality (SHHS: HR: 1.94; 95% CI: 1.18-3.18; P < 0.01; MrOS: HR: 1.66; 95% CI: 1.12-2.47; P = 0.01) after adjusting for covariates. The Shapley Additive Explanations method indicates that low delta wave entropy was more predictive of coronary heart disease, CVD, and CVD mortality risks than conventional sleep parameters. ConclusionsThe results suggest that delta wave activity disruption during sleep may be a useful metric to identify those at increased risk for CVD and CVD mortality.

A Comparative Study of Architecture and Quality of Sleep among Juvenile Myoclonic Epilepsy Patients and Healthy Individuals Attending Tertiary Care Hospital in Central India

&#x0D; &#x0D; &#x0D; &#x0D; Background and Objective: Primary sleep disorders are common in patients with epilepsy. Seizures, epileptiform discharges, and antiepileptic drugs alter the sleep architecture of patients with juvenile myoclonic epilepsy (JME). We evaluated sleep architecture and its quality in these patients.&#x0D; Materials and Methods: Thirty patients with JME (11 men and 19 women with mean age of 21.10 ± 4.55 years) and 30 healthy controls underwent overnight polysomnography (PSG). Sleep quality and daytime sleepiness were assessed using Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS), respectively.&#x0D; Results: Myoclonus and generalized tonic-clonic seizures (GTCS) were present in all patients with JME, while absence seizures were in 13.3%. Sleep deprivation was the most frequent precipitating factor for seizures (56.6%) followed by fatigue, sound, and photic stimulation. Patients with JME reported a statistically significant drop in sleep efficiency (P&lt;0.001) with prolonged sleep onset latency (P&lt;0.001). There was prolongation in the N1 stage of non-rapid eye movement (NREM) sleep (P=0.002), and reduction in the N2 stage of NREM (P&lt;0.001) and rapid eye movement (REM) sleep (P&lt;0.001). The median PSQI score was higher in patients with JME, suggesting poor sleep quality (P&lt;0.001), and the daytime sleepiness was not different as indicated by the similar median ESS score (P=0.033).&#x0D; Conclusion: Our results suggest a significant alteration in the sleep architecture of patients with JME with reduced sleep efficiency and poor sleep quality. The possible role of the disease itself is suggested for these alterations as a simi- lar trend was also observed in drug naïve patients.&#x0D; &#x0D; &#x0D; &#x0D;

Performance Evaluation of a New Sport Watch in Sleep Tracking: A Comparison against Overnight Polysomnography in Young Adults.

Introduction: This study aimed to validate the ability of a prototype sport watch (Polar Electro Oy, FI) to recognize wake and sleep states in two trials with and without an interval training session (IT) 6 h prior to bedtime. Methods: Thirty-six participants completed this study. Participants performed a maximal aerobic test and three polysomnography (PSG) assessments. The first night served as a device familiarization night and to screen for sleep apnea. The second and third in-home PSG assessments were counterbalanced with/without IT. Accuracy and agreement in detecting sleep stages were calculated between PSG and the prototype. Results: Accuracy for the different sleep stages (REM, N1 and N2, N3, and awake) as a true positive for the nights without exercise was 84 ± 5%, 64 ± 6%, 81 ± 6%, and 91 ± 6%, respectively, and for the nights with exercise was 83 ± 7%, 63 ± 8%, 80 ± 7%, and 92 ± 6%, respectively. The agreement for the sleep night without exercise was 60.1 ± 8.1%, k = 0.39 ± 0.1, and with exercise was 59.2 ± 9.8%, k = 0.36 ± 0.1. No significant differences were observed between nights or between the sexes. Conclusion: The prototype showed better or similar accuracy and agreement to wrist-worn consumer products on the market for the detection of sleep stages with healthy adults. However, further investigations will need to be conducted with other populations.

A new dawn: The next frontier in AI-driven sleep enhancement through gradual awakening

Background: Given the prevalence of sleep issues, their impact on overall health and the potential of gradual awakening in mitigating part of the negative effects, innovative solutions can be leveraged to facilitate this awakening process. Objectives: The current study aims to present in detail and validate a novel system that utilizes advanced AI algorithms for sleep tracking, sleep stage prediction, and a "smart alarm" component for optimal gradual awakening. Methods: A clinical trial was conducted to assess the system's effectiveness, namely its influence on several key daily aspects. Participants wearing consumer wearable devices in their sleep were required to self-assess their quality of life, sleep quality and perception of their own waking process through several questionnaires. Results: The integrated system is developed and works as intended. The clinical study findings demonstrate statistically significant benefits in quality of life, sleep quality, user satisfaction with the waking process and mental status upon awakening. On average, an increase in WHOQOL-BREF score from 88.44 to 94.75, a decrease in Sleep Quality Scale scores from 65.66 to 58.19 and in awakening scores from 10.81 to 8.95 (the latter two scores decrease as outcome improves) were observed. Conclusion: Our system shows promise for enhancing individual well-being and productivity by detecting the optimal sleep stage for awakening and providing a more natural waking experience, indicating a valuable direction for future sleep health technologies. Research should be directed at expanding the search for more potential uses, optimizing algorithms and improving user experience.

Sleep Disturbance During Post-Traumatic Amnesia and Early Recovery After Traumatic Brain Injury.

After moderate to severe traumatic brain injury (TBI), sleep disturbance commonly emerges during the confused post-traumatic amnesia (PTA) recovery stage. However, the evaluation of early sleep disturbance during PTA, its recovery trajectory, and influencing factors is limited. This study aimed to evaluate sleep outcomes in patients experiencing PTA using ambulatory gold-standard polysomnography (PSG) overnight and salivary endogenous melatonin (a hormone that influences the sleep-wake cycle) assessment at two time-points. The relationships between PSG-derived sleep-wake parameters and PTA symptoms (i.e., agitation and cognitive disturbance) were also evaluated. In a patient subset, PSG was repeated after PTA had resolved to assess the trajectory of sleep disturbance. Participants with PTA were recruited from Epworth HealthCare's inpatient TBI Rehabilitation Unit. Trained nurses administered overnight PSG at the patient bedside using the Compumedics Somté portable PSG device (Compumedics, Ltd., Australia). Two weeks after PTA had resolved, PSG was repeated. On a separate evening, two saliva specimens were collected (at 24:00 and 06:00) for melatonin testing. Results of routine daily hospital measures (i.e., Agitated Behavior Scale and Westmead PTA Scale) were also collected. Twenty-nine patients were monitored with PSG (mean: 41.6 days post-TBI; standard deviation [SD]: 28.3). Patients' mean sleep duration was reduced (5.6 h, SD: 1.2), and was fragmented with frequent awakenings (mean: 27.7, SD: 15.0). Deep, slow-wave restorative sleep was reduced, or completely absent (37.9% of patients). The use of PSG did not appear to exacerbate patient agitation or cognitive disturbance. Mean melatonin levels at both time-points were commonly outside of normal reference ranges. After PTA resolved, patients (n = 11) displayed significantly longer mean sleep time (5.3 h [PTA]; 6.5 h [out of PTA], difference between means: 1.2, p = 0.005). However, disturbances to other sleep-wake parameters (e.g., increased awakenings, wake time, and sleep latency) persisted after PTA resolved. This is the first study to evaluate sleep disturbance in a cohort of patients as they progressed through the early TBI recovery phases. There is a clear need for tailored assessment of sleep disturbance during PTA, which currently does not form part of routine hospital assessment, to suggest new treatment paradigms, enhance patient recovery, and reduce its long-term impacts.

Caring and therapeutic services – a patient’s opinion on experience and satisfaction with night nursing care

Introduction and aim. Night nursing care ensures well-being, peace, and security allowing a patient to enter into the deep sleep phase. This study aims to analyze the relationship between an assessment of caring and therapeutic services and the opinion of in-patients on their experience and satisfaction with night nursing care. Material and methods. A questionnaire developed by the authors and the Newcastle Satisfaction with Nursing Scale were used in this study. This study was conducted in the eastern region of Poland in the Podkarpackie province. The study included 585 patients. Results. Tasks analyzed resulting from care and therapeutic functions, in the patient’s opinion, had a significant impact on the overall assessment of nursing care. Meeting the expectations regarding night rest (experience of nursing care) and satisfaction showed the strongest correlation. Tasks resulting from therapeutic functions showed an average correlation with the exception of planned medical care. Conclusion. The level of implemented health services by nurses at night significantly influences the overall assessment of the quality management system in health care.

Sleep and Thermoregulation in Birds: Cold Exposure Reduces Brain Temperature but Has Little Influence on Sleep Time and Sleep Architecture in Jackdaws (Coloeus monedula).

Birds have an electrophysiological sleep state that resembles mammalian rapid-eye-movement (REM) sleep. However, whether its regulation and function are similar is unclear. In the current experiment, we studied REM sleep regulation in jackdaws (Coloeus monedula) by exposing the birds to low ambient temperature, a procedure that selectively suppresses REM sleep in mammals. Eight jackdaws were equipped with electrodes to record brain activity and neck muscle activity and a thermistor to record cortical brain temperature. Recordings covered a three-day period starting with a 24 h baseline day at an ambient temperature of 21 °C, followed by a 12 h cold night at 4 °C, after which the ambient temperature was restored to 21 °C for the remaining recovery period. Cold exposure at night caused a significant drop in brain temperature of 1.4 °C compared to the baseline night. However, throughout the cold night, jackdaws expressed NREM sleep and REM sleep levels that were not significantly different from the baseline. Also, EEG spectral power during NREM sleep was unaffected by cold exposure. Thus, while cold exposure had a clear effect on brain temperature in jackdaws, it did not have the same REM sleep suppressing effect reported for mammals. These findings suggest that the REM-sleep-like state in birds, unlike REM sleep in mammals, is protected against the influence of low temperature.

Effect of 60 days of head down tilt bed rest on amplitude and phase of rhythms in physiology and sleep in men

Twenty-four-hour rhythms in physiology and behaviour are shaped by circadian clocks, environmental rhythms, and feedback of behavioural rhythms onto physiology. In space, 24 h signals such as those associated with the light-dark cycle and changes in posture, are weaker, potentially reducing the robustness of rhythms. Head down tilt (HDT) bed rest is commonly used to simulate effects of microgravity but how HDT affects rhythms in physiology has not been extensively investigated. Here we report effects of −6° HDT during a 90-day protocol on 24 h rhythmicity in 20 men. During HDT, amplitude of light, motor activity, and wrist-temperature rhythms were reduced, evening melatonin was elevated, while cortisol was not affected during HDT, but was higher in the morning during recovery when compared to last session of HDT. During recovery from HDT, time in Slow-Wave Sleep increased. EEG activity in alpha and beta frequencies increased during NREM and REM sleep. These results highlight the profound effects of head-down-tilt-bed-rest on 24 h rhythmicity.

Are there effects of light exposure on daytime sleep for rotating shift nurses after night shift?: an EEG power analysis.

Night-shift workers often face various health issues stemming from circadian rhythm shift and the consequent poor sleep quality. We aimed to study nurses working night shifts, evaluate the electroencephalogram (EEG) pattern of daytime sleep, and explore possible pattern changes due to ambient light exposure (30 lux) compared to dim conditions (<5 lux) during daytime sleep. The study involved 31 participants who worked night shifts and 24 healthy adults who had never worked night shifts. The sleep macro and microstructures were analyzed, and electrophysiological activity was compared (1) between nighttime sleep and daytime sleep with dim light and (2) between daytime sleep with dim and 30 lux light conditions. The daytime sleep group showed lower slow or delta wave power during non-rapid eye movement (NREM) sleep than the nighttime sleep group. During daytime sleep, lower sigma wave power in N2 sleep was observed under light exposure compared to no light exposure. Moreover, during daytime sleep, lower slow wave power in N3 sleep in the last cycle was observed under light exposure compared to no light exposure. Our study demonstrated that night shift work and subsequent circadian misalignment strongly affect sleep quality and decrease slow and delta wave activities in NREM sleep. We also observed that light exposure during daytime sleep could additionally decrease N2 sleep spindle activity and N3 waves in the last sleep cycle.

Nocturnal Pressure Controlled Ventilation Improves Sleep Efficiency in Patients Receiving Mechanical Ventilation.

Patients receiving mechanical ventilation commonly experience sleep fragmentation. The present meta-analysis compared the effects of pressure controlled ventilation (PCV) and pressure support ventilation (PSV) on sleep quality. We conducted a search of the PubMed, Embase, and Cochrane Library databases for studies published before November 2023. In this meta-analysis, individual effect sizes were standardized, and the pooled effect size was determined by using random-effects models. The primary outcome was sleep efficiency. The secondary outcomes were wakefulness, percentages of REM (rapid eye movement) sleep and stages 3 and 4 non-REM sleep, the fragmentation index, and the incidence of apneic events. This meta-analysis examined 4 trials that involved 67 subjects. Sleep efficiency was significantly higher in the PCV group than in the PSV group (mean difference 15.57%, 95% CI 8.54%-22.59%). Wakefulness was significantly lower in the PCV group than in the PSV group (mean difference -18.67%, 95% CI -30.29% to -7.04%). The percentage of REM sleep was significantly higher in the PCV group than in the PSV group (mean difference 2.32%, 95% CI 0.20%-4.45%). Among the subjects with a tendency to develop sleep apnea, the fragmentation index was significantly lower in those receiving PCV than PSV (mean difference -40.00%, 95% CI -51.12% to -28.88%). The incidence of apneic events was significantly lower in the PCV group than in the PSV group (risk ratio 0.06, 95% CI 0.01-0.45). Compared with PSV, PCV may improve sleep quality in patients receiving nocturnal mechanical ventilation.

Tripolar concentric ring electrodes for capturing localised electroencephalography signals during sleep.

By design, tripolar concentric ring electrodes (TCRE) provide more focal brain activity signals than conventional electroencephalography (EEG) electrodes placed further apart. This study compared spectral characteristics and rates of data loss to noisy epochs with TCRE versus conventional EEG signals recorded during sleep. A total of 20 healthy sleepers (12 females; mean [standard deviation] age 27.8 [9.6] years) underwent a 9-h sleep study. Participants were set up for polysomnography recording with TCRE to assess brain activity from 18 sites and conventional electrodes for EEG, eyes, and muscle movement. A fast Fourier transform using multitaper-based estimation was applied in 5-s epochs to scored sleep. Odds ratios with Bonferroni-adjusted 95% confidence intervals were calculated to determine the proportional differences in the number of noisy epochs between electrode types. Relative power was compared in frequency bands throughout sleep. Linear mixed models showed significant main effects of signal type (p < 0.001) and sleep stage (p < 0.001) on relative spectral power in each power band, with lower relative spectral power across all stages in TCRE versus EEG in alpha, beta, sigma, and theta activity, and greater delta power in all stages. Scalp topography plots showed distinct beta activation in the right parietal lobe with TCRE versus EEG. EEG showed higher rates of noisy epochs compared to TCRE (1.3% versus 0.8%, p < 0.001). TCRE signals showed marked differences in brain activity compared to EEG, consistent with more focal measurements and region-specific differences during sleep. TCRE may be useful for evaluating regional differences in brain activity with reduced muscle artefact compared to conventional EEG.

A growth chart of brain function from infancy to adolescence based on EEG

In children, objective, quantitative tools that determine functional neurodevelopment are scarce and rarely scalable for clinical use. Direct recordings of cortical activity using routinely acquired electroencephalography (EEG) offer reliable measures of brain function. We developed and validated a measure of functional brain age (FBA) using a residual neural network-based interpretation of the paediatric EEG. In this cross-sectional study, we included 1056 children with typical development ranging in age from 1 month to 18 years. We analysed a 10- to 15-min segment of 18-channel EEG recorded during light sleep (N1 and N2 states). The FBA had a weighted mean absolute error (wMAE) of 0.85 years (95% CI: 0.69-1.02; n=1056). A two-channel version of the FBA had a wMAE of 1.51 years (95% CI: 1.30-1.73; n=1056) and was validated on an independent set of EEG recordings (wMAE=2.27 years, 95% CI: 1.90-2.65; n=723). Group-level maturational delays were also detected in a small cohort of children with Trisomy 21 (Cohen's d=0.36, p=0.028). A FBA, based on EEG, is an accurate, practical and scalable automated tool to track brain function maturation throughout childhood with accuracy comparable to widely used physical growth charts. This research was supported by the National Health and Medical Research Council, Australia, Helsinki University Diagnostic Center Research Funds, Finnish Academy, Finnish Paediatric Foundation, and Sigrid Juselius Foundation.

No Benefit in Memory Performance after Nocturnal Memory Reactivation Coupled with Theta-tACS.

Targeted memory reactivation (TMR) is an effective technique to enhance sleep-associated memory consolidation. The successful reactivation of memories by external reminder cues is typically accompanied by an event-related increase in theta oscillations, preceding better memory recall after sleep. However, it remains unclear whether the increase in theta oscillations is a causal factor or an epiphenomenon of successful TMR. Here, we used transcranial alternating current stimulation (tACS) to examine the causal role of theta oscillations for TMR during non-rapid eye movement (non-REM) sleep. Thirty-seven healthy participants learned Dutch-German word pairs before sleep. During non-REM sleep, we applied either theta-tACS or control-tACS (23 Hz) in blocks (9 min) in a randomised order, according to a within-subject design. One group of participants received tACS coupled with TMR time-locked two seconds after the reminder cue (time-locked group). Another group received tACS in a continuous manner while TMR cues were presented (continuous group). Contrary to our predictions, we observed no frequency-specific benefit of theta-tACS coupled with TMR during sleep on memory performance, neither for continuous nor time-locked stimulation. In fact, both stimulation protocols blocked the TMR-induced memory benefits during sleep, resulting in no memory enhancement by TMR in both the theta and control conditions. No frequency-specific effect was found on the power analyses of the electroencephalogram. We conclude that tACS might have an unspecific blocking effect on memory benefits typically observed after TMR during non-REM sleep.

Sleep and local field potential effect of the D2 receptor agonist bromocriptine during the estrus cycle and postpartum period in female rats

BackgroundPituitary lactotrophs are under tonic dopaminergic inhibitory control and bromocriptine treatment blocks prolactin secretion. MethodsSleep and local field potential were addressed for 72 h after bromocriptine treatments applied during the different stages of the estrus cycle and for 24 h in the early- and middle postpartum period characterized by spontaneously different dynamics of prolactin release in female rats. ResultsSleep changes showed strong dependency on the estrus cycle phase of the drug application. Strongest increase of wakefulness and reduction of slow wave sleep- and rapid eye movements sleep appeared during diestrus-proestrus and middle postpartum treatments.Stronger sleep-wake effects appeared in the dark phase in case of the estrus cycle treatments, but in the light phase in postpartum treatments. Slow wave sleep and REM sleep loss in case of estrus cycle treatments was not compensated at all and sleep loss seen in the first day post-injection was gained further later. In opposition, slow wave sleep loss in the light phase after bromocriptine injections showed compensation in the postpartum period treatments.Bromocriptine treatments resulted in a depression of local field potential delta power during slow wave sleep while an enhancement in beta and gamma power during wakefulness regardless of the treatment timing. ConclusionsThese results can be explained by the interplay of dopamine D2 receptor agonism, lack of prolactin release and the spontaneous homeostatic sleep drive being altered in the different stages of the estrus cycle and the postpartum period.

Generalizable Sleep Staging via Multi-Level Domain Alignment

Automatic sleep staging is essential for sleep assessment and disorder diagnosis. Most existing methods depend on one specific dataset and are limited to be generalized to other unseen datasets, for which the training data and testing data are from the same dataset. In this paper, we introduce domain generalization into automatic sleep staging and propose the task of generalizable sleep staging which aims to improve the model generalization ability to unseen datasets. Inspired by existing domain generalization methods, we adopt the feature alignment idea and propose a framework called SleepDG to solve it. Considering both of local salient features and sequential features are important for sleep staging, we propose a Multi-level Feature Alignment combining epoch-level and sequence-level feature alignment to learn domain-invariant feature representations. Specifically, we design an Epoch-level Feature Alignment to align the feature distribution of each single sleep epoch among different domains, and a Sequence-level Feature Alignment to minimize the discrepancy of sequential features among different domains. SleepDG is validated on five public datasets, achieving the state-of-the-art performance.

Self-Supervised Framework Based on Subject-Wise Clustering for Human Subject Time Series Data

With the widespread adoption of IoT, wearable devices, and sensors, time series data from human subjects are significantly increasing in the healthcare domain. Due to the laborious nature of manual annotation in time series data and the requirement for human experts, self-supervised learning methods are attempted to alleviate the limited label situations. While existing self-supervised methods have been successful to achieve comparable performance to the fully supervised methods, there are still some limitations that need to be addressed, considering the nature of time series data from human subjects: In real-world clinical settings, data labels (e.g., sleep stages) are usually annotated by subject-level, and there is a substantial variation in patterns between subjects. Thus, a model should be designed to deal with not only the label scarcity but also subject-wise nature of data to ensure high performance in real-world scenarios. To mitigate these issues, we propose a novel self-supervised learning framework for human subject time series data: Subject-Aware Time Series Clustering (SA-TSC). In the unsupervised representation learning phase, SA-TSC adopts a subject-wise learning strategy rather than instance-wise learning which randomly samples data instances from different subjects within the batch during training. Specifically, we generate subject-graphs with our graph construction method based on Gumbel-Softmax and perform graph spectral clustering on each subject-graph. In addition, we utilize graph neural networks to capture dependencies between channels and design our own graph learning module motivated from self-supervised loss. Experimental results show the outstanding performance of our SA-TSC with the limited &amp; subject-wise label setting, leading to its high applicability to the healthcare industry. The code is available at: https://github.com/DILAB-HYU/SA-TSC

From land to ocean: One month for southern elephant seal pups to acquire aquatic skills prior to their first departure to sea

Weaned southern elephant seals (SES) quickly transition from terrestrial to aquatic life after a 5- to 6-week post-weaning period. At sea, juveniles and adult elephant seals present extreme, continuous diving behaviour. Previous studies have highlighted the importance of the post-weaning period for weanlings to prepare for the physiological challenges of their future sea life. However, very little is known about how their body condition during this period may influence the development of their behaviour and brain activities. To characterise changes in the behavioural and brain activity of weanlings prior to ocean departure, we implemented a multi-logger approach combining measurements of movements (related to behaviour), pressure (related to diving), and brain electrical activity. As pups age, the amount of time allocated to resting decreases in favour of physical activity. Most resting (9.6 ± 1.2 h/day) takes place during daytime, with periods of slow-wave sleep representing 4.9 ± 0.9 h/day during the first 2 weeks. Furthermore, an increasing proportion of physical activity transitions from land to shore. Additionally, pups in poorer condition (lean group) are more active earlier than those in better condition (corpulent group). Finally, at weaning, clear circadian activity with two peaks at dawn and dusk is observed, and this pattern remains unchanged during the 4 weeks on land. This circadian pattern matches the one observed in adults at sea, with more prey catches at dawn and dusk, raising the question of whether it is endogenous or triggered by the mother during lactation.

The Effects of Sleep Hygiene and Deep Breathing Cough Exercise Training on The Quality of Sleep and Life in COPD Diagnosed Patients

Aim: The purpose of this study was to determine the effects of sleep hygiene and deep breathing-coughing exercise training on the post-discharge quality of sleep and life in COPD diagnosed patients.&#x0D; Materials and Methods: The study was conducted in a group of 30 COPD patients as an intervention group and 30 patients in a control group. A Patient Information Form, the Pittsburgh Sleep Quality Scale (PSQI) and the Quality of Life (SF-36) Scale were administered before deep breathing-coughing exercise and sleep hygiene training were given to patients. In assessing the data, percentages, arithmetic means, chi-square and t-test were used.&#x0D; Results: 70% of the patients in the intervention group were male and their mean age was 64.56±11.37 years; in the control group, 66.67% were male, their mean age was 68.56±12.59 years. Patients in the intervention group had a PSQI pre-training average of 14.20±1.45 and a post-training average of 12.57±0.97; in the control group pre-training average of 15.00±1.89 and a post-training average of 14.80±1.13. The Quality of Life Scale pre-training average of the patients in the intervention group was 43.98±12.72, and their post-training average was 117.12±15.09; in the control group was 36.93±5.77 and their post-training average was 38.13±6.77. There was a statistically significant difference between the pre-test and post-test scores of total PSQI and the Quality of Life Scale in intervention group, but there was no such difference in the control group. &#x0D; Conclusion: Sleep hygiene and deep breathing-coughing exercises training were found to be effective on sleep and quality of life.

Thermoneutral Temperature Exposure Enhances Slow Wave Sleep with a Correlated Improvement in Amyloid Pathology in a Triple-Transgenic Mouse Model of Alzheimer's Disease.

Accumulation of amyloid-β (Aβ) plays an important role in Alzheimer's disease (AD) pathology. There is growing evidence that disordered sleep may accelerate AD pathology by impeding the physiological clearance of Aβ from the brain that occurs in normal sleep. Therapeutic strategies for improving sleep quality may therefore help slow disease progression. It is well documented that the composition and dynamics of sleep are sensitive to ambient temperature. We therefore compared Aβ pathology and sleep metrics derived from polysomnography in 12-month-old female 3xTg-AD mice (n = 8) exposed to thermoneutral temperatures during the light period over four weeks to those of age- and sex-matched controls (n = 8) that remained at normal housing temperature (22⁰C) during the same period. The treated group experienced greater proportions of slow wave sleep (SWS)-i.e., epochs of elevated 0.5-2 Hz slow wave activity during non-rapid eye movement (NREM) sleep-compared to controls. Assays performed on mouse brain tissue harvested at the end of the experiment showed that exposure to thermoneutral temperatures significantly reduced levels of DEA-soluble (but not RIPA- or FA-soluble) Aβ40 and Aβ42 in the hippocampus, though not in the cortex. With both groups pooled together and without regard to treatment condition, NREM sleep continuity and any measure of SWS within NREM at the end of the treatment period were inversely correlated with DEA-soluble Aβ40 and Aβ42 levels, again in the hippocampus but not in the cortex. These findings suggest that experimental manipulation of SWS could offer useful clues into the mechanisms and treatment of AD.