Periods Of Wakefulness Research Articles

Detection of hypotension in patients with syncope: combined tilt test and ambulatory blood pressure monitoring strategy in clinical practice

Abstract Both ambulatory blood pressure monitoring (ABPM) and Tilt Test (TT) (a provocation method), can identify the hypotensive component that predisposes to syncope. Objective 1)To establish a) the prevalence of confirmed hypotension (CHp) with both methods; b) the concordance between them. Methods Patients (pts) ≥18 years with syncope for whom it was decided to perform a TT were included. TT was performed for 45 min at 75 degrees. On a different day, within 15 days, an ABPM was performed (≥70 % adequate readings). Criteria: CHp: In TT: TT(+) or detection of systolic blood pressure (SBP) ≤ 100 mmHg during the study resulting from a drop from baseline; in ABPM: SBP ≤ 100 mmHg resulting from a drop ≥ 20 mmHg from the previous one. Only the awake periods were considered. Results 61 pts (age= 62.5±16.8, female= 39 (64%); antihypertensive medications= 35 pts (57%); Cardiovascular history, except isolated hypertension= 29 pts (47%). The reported number of episodes was 4±4.4 (median=2). Syncope was post-prandial in 25 pts (41%) and probable reflex by the description in 28 pts (46%). CHp during syncope was confirmed in 25 pts during TT and in 1 pt during ABPM. Positive responses to TT were: vasodepressor in 14 pts, mixed in 10 pts and disautonomic pattern in 1 pt. Average 24 h in ABPM was above 135 mmHg in 10 pts (16%). Seventy-nine per cent of the population (48 pts) presented ≥ 2 falls ≥20 mmHg of SBP during the waking period. SBP ≤ 100 mmHg constituted ≥ 20% of awake measurements in 10 pts (16%). A post-prandial fall in SBT ≥ 20 mmHg was detected in 24 patients (39%). Of these, in 8 (13%), the achieved SBP was ≤ 100 mmHg. Table 1 shows the prevalence for CHp with both methods. Table 2 shows the concordance between TT and ABPM. CHp was detected by TT or ABPM in 48 pts, i.e 79% of the population. Both studies were concordant in 32 pts (52%) (Cohen's kappa coefficient: 0.04). CHp was identified in 28% of pts only by TT and in 20% only by ABPM. Conclusion CHp was detected in ¾ of this population using a combined TT and ABPM strategy. They were complementary not only to establish a diagnostic suspicion, but also to guide the therapeutic management of these patients.CHp PrevalenceTT and ABPM Concordance

To compare 24 hour blood pressure values of a conventional 24 hours ambulatory blood pressure device versus a wristband using an artificial intelligence algorithm based on photophletysmography

Abstract Background Ambulatory Blood Pressure Monitoring is of high added value in determining blood pressure, but also highly relevant quantitatively, as hypertension is the single most common medical condition. Unfortunately, practical and qualitative limitations are numerous. Purpose To determine the accuracy of a novel wrist-worn cuff-calibrated photoplethysmography (PPG)-based remote patient monitoring device versus ambulatory blood pressure monitoring (ABPM). Methods The single-center prospective study included 40 adult patients with standard 24-hour ABPM with a 30-minute measurements. Participants used a wrist-worn PPG device during the ABPM period. Measurements of the average difference and standard deviation (SD) for the full 24-hour period as well as for awake and asleep periods were compared. Differences in awake-asleep BP change between the investigational and reference device were described for all, and per nighttime BP dipper category. And also, investigational BP monitoring accuracy under motion will be visualised. Results During the 24-hour period the absolute difference in average SBP and DBP was 3.65 (SD±4.57) and 2.98 (SD±3.91), respectively. Similar results were found for the subsets of day- and nighttime determinations. The absolute difference in average awake-asleep BP change was 2.36 (SD ± 2.40) for SBP and 2.17 (SD ± 2.13) for DBP. Comparable absolute differences were present within each of the nighttime dipper categories. The performance of the investigational device remained stable during motion. Conclusions This study demonstrates initial evidence supporting the accuracy of the evaluated wrist-worn PPG-based device in measuring 24-hour as well as day- and nighttime BP. In the average difference and SD remained within ISO-81060-2:2018 cut-off values from recent ESH guidelines. Therefore, the presented method can provide an accurate and more patient friendly alternative to ABPM.

Acute Effects of Citrulline Malate Supplementation on Nocturnal Blood Pressure Dipping After Exercise in Hypertensive Patients: A Randomized, Placebo-Controlled Trial

Background Citrulline malate (CM), especially when used in conjunction with physical exercise, has demonstrated potential as a non-pharmacological adjunct in the management of hypertension. Nevertheless, its impact on nocturnal blood pressure dipping remains unexplored. Objective Evaluate the impact of a single dose of CM on nocturnal blood pressure dipping after exercise in hypertensive individuals. Methods In a double-blind, placebo-controlled, parallel-group clinical trial, twenty hypertensive adults (55 ± 16 years) were randomly assigned to either a CM (6 g) or placebo (6 g of corn starch) group (PLA). Resting blood pressure was measured after a 20-min period of comfortable seating in a calm environment. Both groups underwent 40 min of treadmill running/walking at an intensity of 60–70% of their reserve heart rate, 120 min after ingesting the substances. Ambulatory blood pressure monitoring was employed to measure blood pressure over 24 h. Results No significant differences in systolic blood pressure values were observed between the CM and PLA groups at rest, during wakefulness, sleep, or over a 24-h period. However, CM exhibited a significant reduction in diastolic blood pressure in several metrics: delta 24 h (-14 mmHg vs −6 mmHg, p = 0.047), delta wakefulness (-12 mmHg vs −4 mmHg, p = 0.024), percent delta 24 h (-16% vs −6%, p = 0.024), and percent delta wakefulness (-14% vs −4%, p = 0.013). No significant differences were found between CM and PLA in terms of systolic and diastolic nocturnal absolute reductions (-13 mmHg vs −12 mmHg, p = 0.808, and −13 mmHg vs −8 mmHg, p = 0.273, respectively) or nocturnal percentage decrease (-9.9% vs −9.4%, p = 0.844, and −15.3% vs −11.7%, p = 0.399, respectively). Conclusions The study found no significant changes in the post-exercise nocturnal blood pressure dip following a single dose of CM supplementation. However, a notable reduction in diastolic blood pressure was observed during the waking period and over the average 24-h monitoring period. Clinical trial registry number and website ClinicalTrials.gov platform (NCT03378596).

Exploring the use of tummy time guidelines to improve infant development in rural primary care

BackgroundTummy time enhances motor development, improves mobility, strength, and head clearance, reduces cranial asymmetry, and decreases the risk of childhood obesity. The American Academy of Pediatrics (AAP) advises all infants, beginning at birth, partake in supervised daily tummy time during awake periods. Since 1994, when the AAP initiated the “Back to Sleep” campaign, the number of infants participating in daily tummy time has significantly declined, leading to an increase in adverse outcomes. MethodsUsing a quasi-experimental design, tummy time guidelines were implemented in a rural family primary care practice to support infant development. This three-phase intervention included educating providers, developing a smart phrase, and posting visual reminders. A convenience sample of infants who presented for well-visits at a rural family practice in southwestern Washington were included in this project. The Survey of Wellbeing of Young Children measurement tool was used to collect infant developmental outcome data. FindingsFollowing the intervention, infant developmental outcomes improved. There was a 10% reduction at two months of age and a 7% reduction at four months of age in the number of infants with below average developmental scores. DiscussionThis project demonstrates that increased provider awareness and implementation of tummy time clinical practice guidelines can benefit infant development in primary care, especially in rural populations. Application to practiceViable strategies for incorporating clinical practice guidelines into primary care are presented.

Morning resting hypothalamus-dorsal striatum connectivity predicts individual differences in diurnal sleepiness accumulation

While the significance of obtaining restful sleep at night and maintaining daytime alertness is well recognized for human performance and overall well-being, substantial variations exist in the development of sleepiness during diurnal waking periods. Despite the established roles of the hypothalamus and striatum in sleep-wake regulation, the specific contributions of this neural circuit in regulating individual sleep homeostasis remain elusive. This study utilized resting-state functional magnetic resonance imaging (fMRI) and mathematical modeling to investigate the role of hypothalamus-striatum connectivity in subjective sleepiness variation in a cohort of 71 healthy adults under strictly controlled in-laboratory conditions. Mathematical modeling results revealed remarkable individual differences in subjective sleepiness accumulation patterns measured by the Karolinska Sleepiness Scale (KSS). Brain imaging data demonstrated that morning hypothalamic connectivity to the dorsal striatum significantly predicts the individual accumulation of subjective sleepiness from morning to evening, while no such correlation was observed for the hypothalamus-ventral striatum connectivity. These findings underscore the distinct roles of hypothalamic connectivity to the dorsal and ventral striatum in individual sleep homeostasis, suggesting that hypothalamus-dorsal striatum circuit may be a promising target for interventions mitigating excessive sleepiness and promoting alertness.

Association between instantaneous heart rate sequence during the awake period and cardiovascular events: a study based on Sleep Heart Health Study.

Heart rate variability (HRV) has been reported to be associated with cardiovascular diseases (CVD), while few studies focused on the instantaneous heart rate (IHR). This study aimed to establish models to predict the occurrence of cardiovascular events based on the IHR sequence. A total of 2977 participants with useful electrocardiogram (ECG) data and free of CVD events at baseline from the Sleep Heart Health Study (SHHS) database were included in this retrospective cohort study. All IHR indicators were measured during the awake period before sleep. The logistic regression, random forest, and XGBoost methods were used to develop the predictive models. The model performance was quantified by calculating the area under the curve (AUC). Of theses 2977 participants, 1460 (49.04%) participants had CVD events during the 15-year follow-up. Higher standard deviation of IHR (SDHR) (OR=0.906; 95% CI, 0.832-0.986), coefficient of variation of IHR (CVHR) (OR=0.910; 95% CI, 0.835-0.990), power in low frequency (LF) (OR=0.896; 95% CI, 0.822-0.975), power in high frequency (HF) (OR=0.872; 95% CI, 0.796-0.955), and total power (TP) (OR=0.887; 95% CI, 0.813-0.967) were associated with the lower risk of CVD events, while ratio of semi-minor axis and semi-major axis in Poincare plot (SDratio) (OR=1.105; 95% CI, 1.012-1.206) was related to the higher risk of CVD events. The AUCs of the logistic regression, random forest, and the XGBoost models were 0.734 (95% CI, 0.701-0.767), 0.794 (95% CI, 0.764-0.823) and 0.828 (95% CI, 0.801-0.855) in the testing set, respectively. IHR sequences were important predictors of cardiovascular events. The IHR indicators should be paid more attention to in future clinical researches on CVD.

Abstract P414: Association between postpartum sleep and blood pressure reduction in women with hypertensive disorders of pregnancy

Importance: It is anticipated that many women do not get enough sleep after delivery. However, it is unclear how poor sleep affects postpartum blood pressure. Objective: To investigate the relationship between postpartum blood pressure and sleep habits, we examined women who developed hypertensive disorders of pregnancy by using automated blood pressure monitors and accelerometers. Setting: The blood pressure, pulse rate, and sleep were monitored at home. Total sleep time, sleep efficiency, sleep fragmentation coefficient, and wake after sleep onset were measured. Participants completed a behavior chart including breastfeeding frequency. The 24-hour, awake time and sleep time mean blood pressures were calculated for each participant as well as the change in blood pressure between postpartum days 7 and 14. Participants: We recruited 11 women who delivered singletons and developed hypertensive disorders of pregnancy at the National Center for Child Health and Development from April to September 2021. Intervention or Exposure: None Main Outcomes: The relationship between the change in blood pressure and sleep measurements and frequency of breastfeeding were analyzed. Results: Seven participants were included in the final analysis. The mean total sleep time was 5.3 hours, and the mean breastfeeding frequency was 6.1 times per day. Mean systolic and diastolic blood pressure and pulse rate during sleep periods tended to be lower than those during awake periods (-8.5±4.5 mmHg, -8.8±2.7 mmHg, -8.7±2.7 bpm, respectively). Lower sleep time was significantly correlated with smaller 24h-systolic and diastolic blood pressure drop (correlation coefficient r=-0.823, p=0.023 and r=-0.812, p=0.026, respectively. No association was found between other sleep measurements and the change in 24h-blood pressure. The blood pressure and pulse rate values in six of the seven participants during the early sleep phase (≤30 min) were similar to those in later sleep phases (>30 min), showing that beneficial effects of sleep on blood pressure were apparent throughout the sleep phases. Conclusions and Relevance: Our results suggest that longer total sleep time, even if sleep is fragmented, is associated with a greater decrease in postpartum blood pressure among women who developed hypertensive disorders of pregnancy.

Multidimensional Sleep Profiles via Machine learning and Risk of Dementia and Cardiovascular Disease.

Sleep health comprises several dimensions such as duration and fragmentation of sleep, circadian activity, and daytime behavior. Yet, most research has focused on individual sleep characteristics. Studies are needed to identify sleep profiles incorporating multiple dimensions and to assess how different profiles may be linked to adverse health outcomes. To identify actigraphy-based 24-hour sleep/circadian profiles in older men and to investigate whether these profiles are associated with the incidence of dementia and cardiovascular disease (CVD) events over 12 years. Data came from a prospective sleep study with participants recruited between 20032005 and followed until 2015-2016. Multicenter population-based cohort study. Among the 3,135 men enrolled, we excluded 331 men with missing or invalid actigraphy data and 137 with significant cognitive impairment at baseline, leading to a sample of 2,667 participants. Leveraging 20 actigraphy-derived sleep and circadian activity rhythm variables, we determined sleep/circadian profiles using an unsupervised machine learning technique based on multiple coalesced generalized hyperbolic mixture modeling. Incidence of dementia and CVD events. We identified three distinct sleep/circadian profiles: active healthy sleepers (AHS; n=1,707 (64.0%); characterized by normal sleep duration, higher sleep quality, stronger circadian rhythmicity, and higher activity during wake periods), fragmented poor sleepers (FPS; n=376 (14.1%); lower sleep quality, higher sleep fragmentation, shorter sleep duration, and weaker circadian rhythmicity), and long and frequent nappers (LFN; n=584 (21.9%); longer and more frequent naps, higher sleep quality, normal sleep duration, and more fragmented circadian rhythmicity). Over the 12-year follow-up, compared to AHS, FPS had increased risks of dementia and CVD events (Hazard Ratio (HR)=1.35, 95% confidence interval (CI)=1.02-1.78 and HR=1.32, 95% CI=1.08-1.60, respectively) after multivariable adjustment, whereas LFN showed a marginal association with increased CVD events risk (HR=1.16, 95% CI=0.98-1.37) but not with dementia (HR=1.09, 95%CI=0.86-1.38). We identified three distinct multidimensional profiles of sleep health. Compared to healthy sleepers, older men with overall poor sleep and circadian activity rhythms exhibited worse incident cognitive and cardiovascular health. These results highlight potential targets for sleep interventions and the need for more comprehensive screening of poor sleepers for adverse outcomes.

The effects of shared, depression-specific, and anxiety-specific internalizing symptoms on negative and neutral episodic memories following post-learning sleep.

Emotional memory bias is a common characteristic of internalizing symptomatology and is enhanced during sleep. The current study employs bifactor S-1 modeling to disentangle depression-specific anhedonia, anxiety-specific anxious arousal, and the common internalizing factor, general distress, and test whether these internalizing symptoms interact with sleep to influence memory for emotional and neutral information. Healthy adults (N = 281) encoded scenes featuring either negative objects (e.g., a vicious looking snake) or neutral objects (e.g., a chipmunk) placed on neutral backgrounds (e.g., an outdoor scene). After a 12-hour period of daytime wakefulness (n = 140) or nocturnal sleep (n = 141), participants judged whether objects and backgrounds were the same, similar, or new compared with what they viewed during encoding. Participants also completed the mini version of the Mood and Anxiety Symptom Questionnaire. Higher anxious arousal predicted worse memory across all stimuli features, but only after a day spent being awake-not following a night of sleep. No significant effects were found for general distress and anhedonia in either the sleep or wake condition. In this study, internalizing symptoms were not associated with enhanced emotional memory. Instead, memory performance specifically in individuals with higher anxious arousal was impaired overall, regardless of emotional valence, but this was only the case when the retention interval spanned wakefulness (i.e., not when it spanned sleep). This suggests that sleep may confer a protective effect on general memory impairments associated with anxiety.

Effects and mechanisms of electroacupuncture on fear extinction and sleep phase in single prolonged stress mice

To observe the effects of electroacupuncture (EA) on fear extinction and sleep phase in single prolonged stress (SPS) mice, and explore its mechanism in view of the expression of relevant synaptic proteins. Thirty-two C57BL/6J male mice were randomly divided into a control group, a model group, an EA group and a paroxetine (PRX) group, with 8 mice in each one. Modified SPS method was used to establish PTSD model in the model group, the EA group and the PRX group. Seven days after modeling completion, in the EA group, the intervention was delivered at "Baihui" (GV 20) and bilateral "Zusanli" (ST 36), with disperse-dense wave, 3 Hz/15 Hz in frequency and 1 mA in current intensity, for 30 min. In the PRX group, paroxetine solution (2.5 g/L) was administered intragastrically (10 mg/kg). The intervention was given once daily and for consecutive 10 days in the above two groups. The fear conditioning task and the elevated plus-maze test were adopted to evaluate the fear extinction and anxiety of the mice in each group. Using Medusa electroencephalogram (EEG) and electromyography (EMG) recording system from rats and mice, the sleep phase was determined in the mice. With Western blot method adopted, the protein expression of the postsynaptic density protein 95 (PSD95), activity-regulated cytoskeleton-associated protein (ARC), brain-derived neurotrophic factor (BDNF), N-methyl-D-aspartic acid receptor 2A (GluN2A), N-methyl-D-aspartic acid receptor 2B (GluN2B) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor 1 (GluA1) in the hippocampus was detected in the mice. Compared with the control group, the freezing time for the fear re-exposure in 3 min to 15 min and the fear extinction in 0 min to 3 min were prolonged (P<0.05), the fear extinction index decreased (P<0.05), and the open arm time (OT) of the elevated plus-maze was shortened (P<0.05) in the model group. When compared with the model group, in the EA group and the PRX group, the freezing time for the fear re-exposure in 3 min to 6 min and 12 min to 15 min, as well as the fear extinction in 0 min to 3 min was shortened (P<0.05), the fear extinction index increased (P<0.05); the OT in elevated plus-maze was longer in the mice of the EA group (P<0.05). The period of wake (Wake) was prolonged (P<0.05), the non-rapid eye movement period (NREM) and the total sleep time (Sleep) were reduced in the model group (P<0.05) in comparison with the control group. Compared with the model group, the Wake was declined (P<0.05), and the NREM and Sleep increased in the EA group and the PRX group (P<0.05). When compared with the control group, the protein expression of PSD95, ARC, BDNF, GluN2A and GluA1 in the hippocampus decreased (P<0.05), and that of GluN2B increased (P<0.05) in the model group. In the EA group and the PRX group, the protein expression of PSD95, ARC, BDNF, GluN2A and GluA1 in the hippocampus was elevated (P<0.05), and that of GluN2B reduced (P<0.05) when compared with the model group. Electroacupuncture at "Baihui" (GV 29) and "Zusanli" (ST 36) can ameliorate anxiety-like behavior, fear extinction disorder and abnormal sleep phase in SPS mice, which may be related to the regulation of synaptic transmission and synaptic plasticity expression in the hippocampus.

Utilizing Multi-Class Classification Methods for Automated Sleep Disorder Prediction

Even from infancy, a human’s day-life alternates from a period of wakefulness to a period of sleep at night, during the 24-hour cycle. Sleep is a normal process necessary for human physical and mental health. A lack of sleep makes it difficult to control emotions and behaviour, reduces productivity at work, and can even increase stress or depression. In addition, poor sleep affects health; when sleep is insufficient, the chances of developing serious diseases greatly increase. Researchers in sleep medicine have identified an extensive list of sleep disorders, and thus leveraged Artificial Intelligence (AI) to automate their analysis and gain a deeper understanding of sleep patterns and related disorders. In this research, we seek a Machine Learning (ML) solution that will allow for efficient classification of unlabeled instances as being Sleep Apnea, Insomnia or Normal (subjects without a specific sleep disorder) by assessing the performance of two well-established strategies for multi-class classification tasks: the One-Vs-All (OVA) and One-Vs-One (OVO). In the context of the specific strategies, two well-known binary classification models were assumed, Logistic Regression (LR) and Support Vector Machines (SVMs). Both strategies’ validity was verified upon a dataset of diverse information related to the profiles (anthropometric data, sleep metrics, lifestyle and cardiovascular health factors) of potential patients or individuals not exhibiting any specific sleep disorder. Performance evaluation was carried out by comparing the weighted average results in all involved classes that represent these two specific sleep disorders and no-disorder occurrence; accuracy, kappa score, precision, recall, f-measure, and Area Under the ROC curve (AUC) were recorded and compared to identify an effective and robust model and strategy, both class-wise and on average. The experimental evaluation unveiled that after feature selection, 2-degree polynomial SVM under both strategies was the least complex and most efficient, recording an accuracy of 91.44%, a kappa score of 84.97%, precision, recall and f-measure equal to 0.914, and an AUC of 0.927.

Effects of meal timing on human plasma metabolite rhythms

The term ‘chrono-nutrition’ describes the interaction between circadian timing and nutritional intake, as demonstrated by a wealth of animal and human studies(1). This relationship is bidirectional, with post-prandial response varying across the day and meal timing acting as a synchronising signal for some circadian rhythms. In humans, we have demonstrated that meal timing is a strong synchroniser of plasma glucose rhythms(2). Our recent data also suggest that interstitial glucose concentration can anticipate large meals(3). However, little is known about the effects of meal timing on other metabolic pathways. The existence of circadian rhythms in human plasma metabolites(4-6) provides a clear opportunity to address this timely issue. Here, in a controlled laboratory protocol, we tested the hypothesis that the anticipation of large meals is observed in human plasma metabolites.Twenty-four male participants undertook an 8-day laboratory study, with strict sleep-wake schedules, light-dark schedules, and food intake. For 6 days, participants consumed either hourly small meals throughout the waking period or two large daily meals (7.5 and 14.5 h after wake-up). Isocaloric meals were calculated using the Mifflin St Jeor formula, and contained 55% carbohydrate, 15% protein, 30% fat(2). All participants then undertook a 37-h constant routine. Samples were collected across a 30-h period in the middle of the constant routine. Plasma was collected every 30 minutes for targeted UPLC-MS/MS metabolomics analysis (Absolute p180 Biocrates kit), and saliva was collected hourly for assessment of melatonin onset, a marker of circadian timing. Data were statistically evaluated by cosinor analysis, unpaired t-test, and repeated measures ANOVA.There was no difference (p &gt;0.05) in melatonin onset between the two groups. Rhythms, as indicated by significant (p &lt; 0.05) cosinor fit, were detected in 64 plasma metabolites (out of 141 detected) in both groups. These metabolites included glucose, triglyceride, cholesterol, plus multiple amino acids, acylcarnitines, phospholipids and sphingolipids. Consistent with previous work, there was a large (c. 7-hour) difference in the phase of plasma glucose between groups, with no significant difference in the phase of plasma triglyceride. Some other metabolites (e.g. histidine and proline) exhibited phase changes like that of glucose, but the phase was mostly unchanged. Glucose, alanine, arginine, citrulline, glutamine, methionine, phenylalanine, met-SO, 3 acylcarnitines and 13 phospholipids exhibited a significant interaction (FDR &lt;0.05 meal-size x time, n=25). Totalcholesterol, asparagine, glutamate, glycine, isoleucine, leucine, ornithine, proline, serine, threonine, tryptophan, tyrosine, kynurenine, SDMA, sarcosine, t4-OH-Pro, taurine, 6 acylcarnitines, 25 phospholipids and SMC18:1 exhibited a significant effect of meal-size and time. A further 8 metabolites had a significant effect of time only. Sixteen metabolites had no significant differences in neither meal size nor time. Our data therefore reveal novel effects of meal timing on multiple metabolite rhythms and average daily concentrations.

Measures of fragmentation of rest activity patterns: mathematical properties and interpretability based on accelerometer real life data

Accelerometers, devices that measure body movements, have become valuable tools for studying the fragmentation of rest-activity patterns, a core circadian rhythm dimension, using metrics such as inter-daily stability (IS), intradaily variability (IV), transition probability (TP), and self-similarity parameter (named α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document}). However, their use remains mainly empirical. Therefore, we investigated the mathematical properties and interpretability of rest-activity fragmentation metrics by providing mathematical proofs for the ranges of IS and IV, proposing maximum likelihood and Bayesian estimators for TP, introducing the activity balance index (ABI) metric, a transformation of α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document}, and describing distributions of these metrics in real-life setting. Analysis of accelerometer data from 2,859 individuals (age=60-83 years, 21.1% women) from the Whitehall II cohort (UK) shows modest correlations between the metrics, except for ABI and α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document}. Sociodemographic (age, sex, education, employment status) and clinical (body mass index (BMI), and number of morbidities) factors were associated with these metrics, with differences observed according to metrics. For example, a difference of 5 units in BMI was associated with all metrics (differences ranging between -0.261 (95% CI -0.302, -0.220) to 0.228 (0.18, 0.268) for standardised TP rest to activity during the awake period and TP activity to rest during the awake period, respectively). These results reinforce the value of these rest-activity fragmentation metrics in epidemiological and clinical studies to examine their role for health. This paper expands on a set of methods that have previously demonstrated empirical value, improves the theoretical foundation for these methods, and evaluates their empirical use in a large dataset.

Towards automatic home-based sleep apnea estimation using deep learning

Apnea and hypopnea are common sleep disorders characterized by the obstruction of the airways. Polysomnography (PSG) is a sleep study typically used to compute the Apnea-Hypopnea Index (AHI), the number of times a person has apnea or certain types of hypopnea per hour of sleep, and diagnose the severity of the sleep disorder. Early detection and treatment of apnea can significantly reduce morbidity and mortality. However, long-term PSG monitoring is unfeasible as it is costly and uncomfortable for patients. To address these issues, we propose a method, named DRIVEN, to estimate AHI at home from wearable devices and detect when apnea, hypopnea, and periods of wakefulness occur throughout the night. The method can therefore assist physicians in diagnosing the severity of apneas. Patients can wear a single sensor or a combination of sensors that can be easily measured at home: abdominal movement, thoracic movement, or pulse oximetry. For example, using only two sensors, DRIVEN correctly classifies 72.4% of all test patients into one of the four AHI classes, with 99.3% either correctly classified or placed one class away from the true one. This is a reasonable trade-off between the model’s performance and the patient’s comfort. We use publicly available data from three large sleep studies with a total of 14,370 recordings. DRIVEN consists of a combination of deep convolutional neural networks and a light-gradient-boost machine for classification. It can be implemented for automatic estimation of AHI in unsupervised long-term home monitoring systems, reducing costs to healthcare systems and improving patient care.

Modafinil Subjectively Does Not Impair Sleep in Aviators After a Period of Extended Wakefulness.

INTRODUCTION: Modafinil is used as a countermeasure to limit the effects of fatigue in military aviation. However, literature is conflicting about its negative effects on subsequent sleep.METHODS: This randomized placebo-controlled trial conducted by the Center of Man in Aviation of the Royal Netherlands Airforce is part of a larger study. It included 32 subjects (mean age 35 yr old, 84% male) who followed a normal daily routine and stayed awake the subsequent night. At midnight, all subjects received either 300 mg caffeine, 200 mg modafinil, or placebo. At the end of the test night, subjects were awake for a median period of 26 h. Afterwards, sleep questionnaires containing qualitative (Groningen Sleep Quality Scale) and quantitative parameters of sleep for the subsequent day (recovery sleep) and consecutive night (post-test sleep) were completed and statistically analyzed using Friedman and Wilcoxon signed rank tests.RESULTS: A statistically significant difference in the reported recovery sleep was observed. The modafinil group slept 30% shorter than placebo, but sleep efficiency was not statistically different. Quantitatively post-test sleep did not vary statistically significantly between the three groups. However, Groningen Sleep Quality Scale scores were lower post-test than pre-test in the modafinil group, while this was not the case in the caffeine and placebo group.DISCUSSION:This study found that modafinil subjectively does not negatively impact recovery sleep or subsequent nighttime sleep after an extended period of wakefulness and suggests it may decrease the need for recovery sleep compared to placebo or caffeine.Wingelaar-Jagt YQ, Wingelaar TT, Riedel WJ, Ramaekers JG. Modafinil subjectively does not impair sleep in aviators after a period of extended wakefulness. Aerosp Med Hum Perform. 2024; 95(6):290-296.

Acute increases in physical activity and temperature are associated with hot flash experience in midlife women.

This study determined the association between acute changes in physical activity, temperature, and humidity and 24-hour subjective and objective hot flash experience. Data collection occurred during the cooler months of the year in Western Massachusetts (October-April). Women aged 45-55 across three menopause stages (n = 270) were instrumented with ambulatory monitors to continuously measure hot flashes, physical activity, temperature, and humidity for 24 hours. Objective hot flashes were assessed via sternal skin conductance, and subjective hot flashes were recorded by pressing an event marker and data logging. Physical activity was measured with wrist-worn accelerometers and used to define sleep and wake periods. Logistic multilevel modeling was used to examine the differences in physical activity, humidity, and temperature in the 10 minutes preceding a hot flash versus control windows when no hot flashes occurred. The odds of hot flashes were considered separately for objective and subjective hot flashes as well as for wake and sleep periods. Data from 188 participants were included in the analyses. There was a significantly greater odds of a hot flash following acute increases in physical activity for objective waking hot flashes (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.17-1.47; P < 0.001) and subjective waking hot flashes (OR, 1.16; 95% CI, 1.0-1.33; P = 0.03). Acute increases in the actigraphy signal were associated with significantly higher odds of having an objective (OR, 1.17; 95% CI, 1.03-1.35; P < 0.01) or subjective (OR, 1.72; 95% CI, 1.52-2.01; P < 0.001) sleeping hot flash. Increases in temperature were significantly related to the odds of subjective sleeping hot flashes only (OR, 1.38; 95% CI, 1.15-1.62; P < 0.001). There was no evidence for a relationship between humidity and odds of experiencing any hot flashes. These results indicate that acute increases in physical activity increase the odds of hot flashes that are objectively measured and subjectively reported during waking and sleeping periods. Temperature increases were only related to subjectively reported nighttime hot flashes.

The impact of sleep on factual memory retention over 24 hr.

Although a period of sleep seems to benefit the retention of declarative memories, recent studies have challenged both the size of this effect and its active influence on memory consolidation. This study aimed to further investigate the effect of sleep and its time dependency on the consolidation of factual information. In a within-subjects design, 48 participants (Mage = 24.37 ± 4.18 years, 31F) were asked to learn several facts in a multi-sensory "flashcard-like" memory task at 21:00 hours (sleep first condition) or at 09:00 hours (wake first condition). Then, in each condition, participants performed an immediate recall test (T0), and two delayed tests 12 hr (T1) and 24 hr (T2) later. Participants' sleep was recorded at their homes with a portable device. Results revealed that memory retention was better after a night of sleep compared with wakefulness, regardless of the delay from encoding (a few hr versus 12+ hr), but the sleep effect was modest. The decline in memory during the wake period following sleep was smaller compared with the decline observed during the 12 hr of wakefulness after encoding. However, after 24 hr from the encoding, when all participants experienced a period of both sleep and wakefulness, memory performance in the two conditions was similar. Overall, our data suggest that sleep exerts a small, yet beneficial, influence on memory retention by likely reducing interference and actively stabilizing memory traces.

Représentations et pratiques nocturnes dans la société roumaine (XVIIIe – XXe siècles)

Folklorists, ethnographers and anthropologists have dedicated few studies to the night, and they especially emphasized its negative representations: an interval of darkness, of anxiety and fear, a time of intensified activities of evil supernatural forces. By favoring imaginary and mythical components, night was taken into consideration as an exceptional and extraordinary time, as a negative counterpart to the day, and not as a natural reverse of it. For a long time, the night did not draw the attention of historians, being perceived as a time when nothing happens, a time for rest and sleep. Starting with Jean Verdon’s pioneering book (“La Nuit au Moyen Âge”, 1994), historians have become increasingly interested in night habits, and explored the nightlife of people in ancient societies, bedtimes and waking times, sleep duration. The history of sleep has become a new field of research, opened by the American historian Roger Ekirch (2001, 2005), who advanced the theory that people in pre-industrial societies used to sleep differently. During the night, the sleep was biphasic (or segmented), divided into two moments and separated by a period of wakefulness (watch) at around midnight (between the first sleep and the second one). In our study we intend to verify if the results of Ekirch’s research are also applicable to the realities of the Romanian society in the 18th-20th centuries. We must recognize the difficulties of a history of nocturnal time, the fragmentary nature of the sources, the lack of direct and explicit testimonies (few people have been able to subjectivize their experience of sleep and transmit written testimonies). Therefore, we investigated sources such as chronicles, judiciary documents and literary texts, in search of the segmented sleep pattern. We have identified direct or indirect references to the two periods of sleep, and the intervening period of wakefulness. These references allow us to cautiously advance the hypothesis that this sleep pattern also existed in pre-modern Romanian society, in rural and urban environments. The future researches, based on teamwork, will more accurately determine the validity of this hypothesis.

Sleep stage continuity is associated with objective daytime sleepiness in patients with suspected obstructive sleep apnea.

Excessive daytime sleepiness (EDS) in patients with obstructive sleep apnea (OSA) is poorly explained by standard clinical sleep architecture metrics. We hypothesized that reduced sleep stage continuity mediates this connection independently from standard sleep architecture metrics. 1,907 patients with suspected OSA with daytime sleepiness complaints underwent in-lab diagnostic polysomnography and next-day Multiple Sleep Latency Test (MSLT). Sleep architecture was evaluated with novel sleep-stage continuity quantifications (mean sleep stage duration and probability of remaining in each sleep stage), and conventional metrics (total N1, N2, N3 and REM times; and sleep onset latency). Multivariate analyses were utilized to identify variables associated with moderate EDS (5 ≤ mean daytime sleep latency (MSL) ≤ 10 minutes) and severe EDS (MSL < 5 minutes). Compared to those without EDS, participants with severe EDS had lower N3 sleep continuity (mean N3 period duration 10.4 vs 13.7 minutes, p<0.05), less N3 time (53.8 vs 76.5 minutes, p<0.05); greater total sleep time (374.0 vs 352.5 minutes, p<0.05) and greater N2 time (227.5 vs 186.8 minutes, p<0.05). After adjusting for standard sleep architecture metrics using multivariate logistic regression, decreased mean wake and N3 period duration, and the decreased probability of remaining in N2 and N3 sleep remained significantly associated with severe EDS, while the decreased probability of remaining in wake and N2 sleep were associated with moderate EDS. Patients with OSA with EDS experience lower sleep continuity, noticeable especially during N3 sleep and wake. Sleep-stage continuity quantifications assist in characterizing the sleep architecture and are associated with objective daytime sleepiness highlighting the need for more detailed evaluations of sleep quality.

Affect and satisfaction time dependency: An experience sampling study.

The aim of this study was to test the time dependency between affect and satisfaction on a momentary level. Ninety-eight students participated in the study, using the experience sampling method. Affect and satisfaction scales were administered five times a day for 7 days via handheld devices, sampling the whole awake period with ratings approximately 3-4 h apart. The aim of this study was to examine the cross-correlation between affect and satisfaction at the intra-individual level and to test their temporal consistency via lagged cross-correlations. On average, satisfaction was robustly associated with positive affect (PA; mean correlation 0.50) and negative affect (NA; mean correlation -0.38). The correlation of satisfaction with affect factors showed a consistent temporal dependency. Lag (i.e., the shift of one time series with respect to another) significantly affected the magnitude of the correlation coefficients of satisfaction with PA and NA (explaining almost half of the correlation variance). A significant affect-satisfaction cross-correlation can be found when no lag is present. The introduction of a lag reduces the affect-satisfaction cross-correlation to virtually zero. Research suggests that affect and satisfaction overlap at the momentary level, and the results of this study imply that they are also time-dependent. These findings corroborate the idea that momentary satisfaction judgments are partially based on available emotional information, both in terms of intensity and temporal consistency.