Physiological markers of sleep quality: A scoping review

Longitudinal association of sleep quality with physical performance measures: SABE cohort study, Brazil

OBJECTIVES

The aim of this study was to investigate the longitudinal association of sleep with physical performance in a representative sample of non-institutionalised older adults residing in the municipality of São Paulo, Brazil.

STUDY DESIGN

Prospective cohort study.

METHODS

The current longitudinal study used data extracted from the Health, Well-being, and Aging Study (Estudo Saúde Bem-Estar e Envelhecimento [SABE]). The study population consisted of individuals aged ≥60 years who participated in the study in 2010 or 2015. Dependent variables included the Short Physical Performance Battery (SPPB) and gait speed. Independent variables of interest were self-reported sleep difficulty, daytime sleepiness and sleep quality. The longitudinal association between sleep variables and the outcomes was evaluated using Generalised Estimating Equations (GEE) Models adjusted for covariates. All the variables, except age, sex and schooling, were assessed at baseline and follow-up visits (2010 and 2015).

RESULTS

The analyses included 2205 observations from 1559 individuals. The population mean age was 72 years in 2010 and 71 years in 2015, with a higher prevalence of women in both years. Between 2010 and 2015, there was a decline in the SPPB score and gait speed. Daytime sleepiness was negatively associated with the SPPB score [Coef.: -0.38 (95% confidence interval {CI}: -0.56, -0.21)] and gait speed [Coef.: -0.03 (95% CI: -0.05, -0.01)]. Poor sleep quality was negatively associated with the SPPB score [Coef.: -0.29 (95% CI: -0.57, -0.01)] and gait speed [Coef.: -0.03 (95% CI: -0.06, -0.00)].

CONCLUSIONS

Daytime sleepiness and poor sleep quality are associated with compromised physical performance in non-institutionalised older adults, and this association remained consistent over time.

Effect of cognitive behavioral therapy for insomnia on sleep quality among college students: the role of hyperarousal and dysfunctional beliefs

BACKGROUND

Although cognitive-behavioral therapy for insomnia (CBT-I) is an effective treatment for sleep disorders, little is known about the role of hyperarousal (especially trait arousal) in CBT-I interventions. Therefore, this study investigated the role of trait arousal in the maintenance of sleep problems using cross-sectional and longitudinal methods.

METHODS

Study 1, 1209 Chinese university students (63.9% female) completed the Dysfunctional Beliefs and Attitudes about Sleep (DBAS-16), Pre-sleep Arousal Scale (PSAS), Arousal Predisposition Scale (APS), and Pittsburgh Sleep Quality Index (PSQI). The study calculated the moderating role of trait arousal in the relationship between dysfunctional beliefs about sleep and sleep quality. In study two, 89 participants completed the questionnaire used in Study 1 during pre-and post-treatment. A within-subjects mediation analysis examined the indirect effects of dysfunctional beliefs about sleep pre-sleep arousal (cognitive and somatic) on sleep quality. A within-subjects moderation analysis was used to investigate whether baseline trait arousal moderated sleep quality.

RESULTS

Cross-sectional findings indicated that pre-sleep cognitive arousal mediated the effects of dysfunctional beliefs about sleep on sleep quality and that trait arousal moderated the first half of the mediating pathway described above; longitudinal analyses indicated that changes in dysfunctional beliefs about sleep and pre-sleep cognitive arousal mediated changes in sleep quality, and that, in addition, trait arousal moderated changes in sleep quality.

CONCLUSION

Trait arousal correlates with the maintenance of sleep problems, and participants with higher trait arousal benefited less from CBT-I. Enhancement programs that incorporate mindfulness may be a direction for future research.

Current situation and relationship between occupational stress, burn-out and sleep quality among ambulance drivers: a cross-sectional study

OBJECTIVE

To understand the current status of occupational stress, occupational burn-out and sleep quality among ambulance drivers in Hengyang, China and to analyse the relationship between occupational stress, occupational burn-out and sleep quality of ambulance drivers.

DESIGN

A cross-sectional study.

SETTING

Prehospital emergency centre of third-class hospital in Hengyang, China.

PARTICIPANTS

From October 2023 to December 2023, a cross-sectional survey was conducted, with 213 ambulance drivers from Hengyang, China, selected as participants.

METHODS

General demographic questionnaires, the Chinese Occupational Stress Inventory, the Maslach Burnout Inventory and the Pittsburgh Sleep Quality Index were used for data collection and analysis.

RESULTS

Occupational stress among ambulance drivers was positively correlated with occupational burn-out and sleep quality (r=0.528, 0.447, both p<0.01) while occupational burn-out was positively correlated with sleep quality (r=0.394, p<0.01). Occupational burn-out partially mediated the relationship between occupational stress and sleep quality among ambulance drivers, with a mediation effect value of 0.168, accounting for 26.09% of the total effect.

CONCLUSION

The sleep quality of ambulance drivers in Hengyang, China is suboptimal, with occupational stress directly predicting sleep quality. Occupational burn-out plays a partial positive mediating role between occupational stress and sleep quality among ambulance drivers. Reducing occupational stress and burn-out is beneficial for improving the sleep quality of ambulance drivers.

Increased training load promotes sleep propensity and slow-wave sleep in endurance runners: Can a high-heat-capacity mattress topper modulate this effect?

The present study aimed to: (1) investigate sleep architecture in response to an overload training and taper periods among endurance runners; and (2) assess the sleep benefits of a high-heat-capacity mattress topper. Twenty-one trained male endurance runners performed a 2-week usual training regimen (baseline) followed by 2-week overload and taper periods. From overload to the end of the taper period, they were assigned into two groups based on the mattress topper used: high-heat-capacity mattress topper (n = 11) or low-heat-capacity mattress topper (n = 10). Training load was assessed daily using the session rating of perceived exertion. Following each period, sleep was monitored by polysomnography, and nocturnal core body temperature was recorded throughout the night. Irrespective of the group, awakening episodes > 5 min decreased following overload compared with baseline (-0.48, p = 0.05). Independently of mattress topper, each 100 A.U. increase in 7-day training load prior to polysomnographic recording was associated with higher slow-wave sleep proportion (β = +0.13%; p = 0.05), lower sleep-onset latency (β = -0.49 min; p = 0.05), and a reduction in the probability of transition from N1 sleep stage to wakefulness (β = -0.12%; p = 0.05). Sleeping on a high-heat-capacity mattress topper did not affect any sleep variable compared with a low-heat-capacity mattress topper. Increased training loads promote slow-wave sleep and sleep propensity, highlighting the adaptative nature of sleep to diurnal activity and the role of sleep in physiological recovery. Further studies are required on the potential benefits of high-heat-capacity mattress toppers on sleep architecture among athletes.

Louis EK, Ruoff CM, Kolla BP. Aging and sex are associated with multiple sleep latency test findings and their relationship with self-reported sleepiness

The aim of this study was to assess age- and sex-related differences in multiple sleep latency test (MSLT) results and in the performance of the Epworth Sleepiness Scale (ESS) at classifying objective hypersomnia (mean sleep latency (MSL) ≤ 8 min). We studied 480 consecutive adults (39.3 ± 15.3 years old [18-93], 67.7% female) who underwent hypersomnia evaluation. We fit linear regression models to investigate associations between age and sex and sleep latencies (mean and for every nap), after adjusting for total sleep time and sleep efficiency (on polysomnography), and REM-suppressing antidepressant effect. A logistic regression was performed to assess whether age and sex were associated with sleep-onset REM period (SOREMP) occurrence. ROC analysis assessed the diagnostic performance of ESS scores to identify a MSL ≤ 8 min in different age/sex groups. For every 10 years of age, there was 0.41 (95% CI 0.11-0.72, p = 0.008) min reduction in MSL. Objectively (MSL ≤ 8 min) sleepy patients had shortening of latencies in naps 4 and 5 with aging. Female sex was associated with a higher MSL only in patients with MSL > 8 min. A 2.4% reduction in the odds of SOREMP occurrence was observed for every year of age in objectively sleepy patients (p = 0.045). ESS scores had a better diagnostic performance in older (≥ 50 years old) men than younger (< 50 years old) women (p < 0.05). Older patients with objectively confirmed hypersomnia may be sleepier in later naps, possibly due to less restorative naps and/or circadian rhythm factors. Self-reported sleepiness is more predictive of objective sleepiness in older men than younger women.

Polysomnographic parameters associated with cognitive function in patients with major depression and insomnia

OBJECTIVE

To examine whether objective sleep parameters are associated with cognitive function (CF) in patients with major depressive disorder (MDD) with chronic insomnia (CI) and whether the severity of these disorders is related to CF.

METHOD

Thirty patients with MDD with CI attending a tertiary care institution underwent two consecutive nights of polysomnographic (PSG) recording and a battery of neuropsychological tests, which included episodic memory, sustained attention, working memory, and executive function. The severity of MDD and CI was assessed by clinical scales. We examined the relationship between PSG parameters and CF, as well as whether the severity of the disorders is related to CF.

RESULTS

Linear regression analysis revealed that total sleep time (TST) was positively associated with higher learning and recall of episodic memory, as well as better attention. Slow-wave sleep (SWS) showed a positive association with better working memory. Furthermore, wake after sleep onset (WASO) was negatively associated with episodic memory and lower attention. No significant relationships were found between the severity of MDD or CI with CF.

CONCLUSION

Both sleep duration and depth are positively associated with several aspects of CF in patients with MDD with CI. Conversely, a lack of sleep maintenance is negatively related to CF in these patients. These findings could help identify modifiable therapeutic targets to reduce CF impairment.

The Emerging Importance of Sleep Regularity on Cardiovascular Health and Cognitive Impairment in Older Adults: A Review of the Literature

The regularity of sleep/wake patterns across multiple days is emerging as an important determinant of health. However, the association between sleep regularity and health outcomes in the aging population is not well understood. The current systematic review identified 22 publications that examined the relationship between sleep regularity and selected health outcomes: cardiovascular risk, cognitive impairment, and mortality. All studies were published after 2010, reflecting a growing research interest in daily sleep regularity. Low sleep regularity was consistently associated with higher cardiovascular risk and elevated risk of all-cause mortality. Results on cognitive impairment are mixed, with inconsistency likely attributed to small sample sizes and differences in sleep regularity assessment. Overall, regularity in sleep carries important information about health and should be included in future studies that collect daily sleep measures. Gaps in literature and methodological shortcomings are discussed.

The Relationships Among Family Functioning, Sleep Quality and Quality of Life in Chinese Community-Dwelling Older Adults with Insomnia: A Structural Equation Model

OBJECTIVES

The proportion of individuals with insomnia is increasing, and many older adults have insomnia. This study aimed to explore the relationships between family functioning and quality of life (QOL) among community-dwelling older adults with insomnia, as well as to explore the mediating role of sleep quality in this relationship.

METHODS

The participants were 225 older adults with insomnia from community health service centers in Chongqing, China. The Family Care Index (APGAR) was used to assess family functioning, the Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep quality, and the 36-item Short-Form Health Survey (SF-36) was used to assess QOL.

RESULTS

The results showed that family functioning would be positively associated with QOL (p = .005) and that this relationship would be partially mediated by higher sleep quality (p < .001).

CONCLUSIONS

Family functioning has a direct effect on QOL and an indirect effect on QOL through the regulation of sleep quality. Maintaining good family functioning is important for improving sleep quality and QOL in older adults with insomnia.

CLINICAL IMPLICATIONS

Developing family functioning-based assessments and targeted intervention strategies could be beneficial for older adults with insomnia.

Resilience provides mediating effect of resilience between fear of progression and sleep quality in patients with hematological malignancies

BACKGROUND

Hematological tumors are common malignant tumors, with high morbidity and mortality rates. Most patients with hematological malignancies develop sleep disorders that seriously affect their life and health because of acute onset of disease, rapid progression, high recurrence rates, complex treatment methods, and treatment costs.

AIM

To explore the mediating effect of resilience on fear of disease progression and sleep quality in patients with hematological malignancies.

METHODS

A cross-sectional analysis of 100 patients with hematological malignancies, treated in the First Affiliated Hospital of Jinzhou Medical University between August 2022 and August 2023, was conducted. Patients were assessed using a general data survey, a simplified scale for the fear of progression (FoP) of disease, a resilience scale, and the Pittsburgh Sleep Quality Index. Statistical analysis was conducted to determine the relationship between various patient characteristics and FoP, resilience, and sleep quality. Spearman's correlation analysis was used to examine the correlations between mental resilience, FoP, and sleep quality.

RESULTS

The total FoP score mean value in patients with hematological malignancies was 38.09 ± 5.16; the total resilience score mean value was 40.73 ± 7.04; and the Pittsburgh Sleep Quality Index score mean value was 10.72 ± 1.90. FoP, resilience, and sleep quality of the patients were associated with family per capita monthly income and patient education level (P < 0.05). Spearman correlation analysis revealed that FoP was negatively correlated with resilience and sleep quality scores (r = -0.560, -0.537, P < 0.01), respectively, and resilience was significantly associated with sleep quality scores (r = 0.688, P < 0.01). Mediation analysis showed that the mediating effect of resilience between FoP and sleep quality in patients with hematological malignancies was -0.100 and accounted for 50.51% of the total effect. This indicated that FoP directly and indirectly affected sleep quality through the mesomeric effect of resilience.

CONCLUSION

Resilience is an intermediary variable between FoP and sleep quality in patients with hematological malignancies. Medical staff should evaluate and follow-up FoP and resilience to implement measures to improve sleep quality.

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

Purpose

Female athletes with menstrual abnormalities have poor sleep quality. However, whether female athletes with poor sleep quality based on subjective assessment have distinctive changes in objective measures of sleep in association with menses remains unclear. This study aimed to compare changes in objective sleep measurements during and following menses between collegiate female athletes with and without poor subjective sleep quality.

Patients and Methods

Female collegiate athletes (age range/mean ± standard deviation: 18-22/ 22.2±1.1) with regular menstrual cycles were recruited. The participants underwent home electroencephalogram monitoring during the first and second nights after the onset of menses and one night between the seventh and 10th nights after menses onset (mid-follicular phase). The Pittsburgh Sleep Quality Index (PSQI) was used to assess the subjective sleep quality. Interactions between the presence of poor subjective sleep quality (ie, PSQI ≥6) and changes in objective measures of sleep in association with menses were analyzed.

Results

Data of 45 athletes, including 13 with poor subjective sleep quality, showed that changes in arousal index in athletes with poor subjective sleep quality were distinctive from those in athletes without poor subjective sleep quality (p = 0.036 for interaction). In athletes with poor subjective sleep quality, the arousal index was significantly increased in menses (p for analysis of variance, 0.015), especially on the first night after the onset of menses compared with during the mid-follicular phase (p = 0.016).

Conclusion

Collegiate female athletes with regular menstrual cycles are likely to have poor subjective sleep quality in association with more frequent arousal during the first night after the onset of menses than during the mid-follicular phase.

Trajectories of sleep duration and quality and their association with mild cognitive impairment, frailty, and all-cause mortality

OBJECTIVES

To identify longitudinal trajectories of sleep duration and quality and estimate their association with mild cognitive impairment, frailty, and all-cause mortality.

METHODS

We used data from three waves (2009, 2014, 2017) of the WHO Study on Global Aging and Adult Health in Mexico. The sample consisted of 2722 adults aged 50 and over. Sleep duration and quality were assessed by self-report. Sleep trajectories were determined by applying growth mixture models. Mixed-effects logistic (mild cognitive impairment) and ordinal logistic (frailty), and Cox proportional hazards (all-cause mortality) models were fitted.

RESULTS

Three classes for sleep duration ("optimal-stable," "long-increasing," and "short-decreasing") and quality ("very good-increasing," "very good-decreasing," and "moderate/poor stable") were identified. Compared to the optimal-stable group, the long-increasing trajectory had greater odds for mild cognitive impairment (odds ratio=1.68, 95% CI: 1.01-2.78) and frailty (odds ratio=1.66, 95% CI: 1.13-2.46), and higher risk for all-cause mortality (hazard ratio=1.91, 95% CI: 1.14-3.19); and the short-decreasing class had a higher probability of frailty (odds ratio=1.83, 95% CI: 1.26-2.64). Regarding the sleep quality, the moderate/poor stable trajectory had higher odds of frailty (odds ratio=1.71, 95% CI: 1.18-2.47) than very good-increasing group.

CONCLUSIONS

These results have important implications for clinical practice and public health policies, given that the evaluation and treatment of sleep disorders need more attention in primary care settings. Interventions to detect and treat sleep disorders should be integrated into clinical practice to prevent or delay the appearance of alterations in older adults' physical and cognitive function. Further research on sleep quality and duration is warranted to understand their contribution to healthy aging.

Objective sleep quality predicts subjective sleep ratings

In both clinical and observational studies, sleep quality is usually assessed by subjective self-report. The literature is mixed about how accurately these self-reports track objectively (e.g. via polysomnography) assessed sleep quality, with frequent reports of little to no association. However, previous research on this question focused on between-subject designs, which may be confounded by trait-level variables. In the current study, we used the novel Budapest Sleep, Experiences and Traits Study (BSETS) dataset to investigate if within-subject differences in subjectively reported sleep quality are related to sleep macrostructure and quantitative EEG variables assessed using a mobile EEG headband. We found clear evidence that self-reported sleep quality in the morning is influenced by within-subject variations in sleep onset latency, wake after sleep onset, total sleep time, and sleep efficiency. These effects were replicated if detailed sleep composition metrics (percentage and latency of specific vigilance states) or two alternative measures of subjective sleep quality were used instead. We found no effect of the number of awakenings or relative EEG delta and sigma power. Between-subject effects (relationships between individual mean values of sleep metrics and subjective sleep quality) were also found, highlighting that analyses focusing only on these may be erroneous. Our findings show that while previous investigations of this issue may have been confounded by between-subject effects, objective sleep quality is indeed reflected in subjective sleep ratings.

Association between alcohol consumption and sleep traits: observational and mendelian randomization studies in the UK biobank

Previous studies have shown that excessive alcohol consumption is associated with poor sleep. However, the health risks of light-to-moderate alcohol consumption in relation to sleep traits (e.g., insomnia, snoring, sleep duration and chronotype) remain undefined, and their causality is still unclear in the general population. To identify the association between alcohol consumption and multiple sleep traits using an observational and Mendelian randomization (MR) design. Observational analyses and one-sample MR (linear and nonlinear) were performed using clinical and individual-level genetic data from the UK Biobank (UKB). Two-sample MR was assessed using summary data from genome-wide association studies from the UKB and other external consortia. Phenotype analyses were externally validated using data from the National Health and Nutrition Examination Survey (2017-2018). Data analysis was conducted from January 2022 to October 2022. The association between alcohol consumption and six self-reported sleep traits (short sleep duration, long sleep duration, chronotype, snoring, waking up in the morning, and insomnia) were analysed. This study included 383,357 UKB participants (mean [SD] age, 57.0 [8.0] years; 46% male) who consumed a mean (SD) of 9.0 (10.0) standard drinks (one standard drink equivalent to 14 g of alcohol) per week. In the observational analyses, alcohol consumption was significantly associated with all sleep traits. Light-moderate-heavy alcohol consumption was linearly linked to snoring and the evening chronotype but nonlinearly associated with insomnia, sleep duration, and napping. In linear MR analyses, a 1-SD (14 g) increase in genetically predicted alcohol consumption was associated with a 1.14-fold (95% CI, 1.07-1.22) higher risk of snoring (P < 0.001), a 1.28-fold (95% CI, 1.20-1.37) higher risk of evening chronotype (P < 0.001) and a 1.24-fold (95% CI, 1.13-1.36) higher risk of difficulty waking up in the morning (P < 0.001). Nonlinear MR analyses did not reveal significant results after Bonferroni adjustment. The results of the two-sample MR analyses were consistent with those of the one-sample MR analyses, but with a slightly attenuated overall estimate. Our findings suggest that even low levels of alcohol consumption may affect sleep health, particularly by increasing the risk of snoring and evening chronotypes. The negative effects of alcohol consumption on sleep should be made clear to the public in order to promote public health.

Physiological evidence of stress reduction during a summer Antarctic expedition with a significant influence of previous experience and vigor

Antarctica provides a unique environment for studying human adaptability, characterized by controlled conditions, limited sensory stimulation, and significant challenges in logistics and communication. This longitudinal study investigates the relationship between stress indicators, with a specific focus on mean sleep heart rate, during a COVID-19 quarantine and subsequent 83 days long summer Antarctic expedition at the J. G. Mendel Czech Antarctic Station. Our novel approach includes daily recordings of sleep heart rate and weekly assessments of emotions, stress, and sleep quality. Associations between variables were analyzed using the generalized least squares method, providing unique insights into nuances of adaptation. The results support previous findings by providing empirical evidence on the stress reducing effect of Antarctic summer expedition and highlight the importance of previous experience and positive emotions, with the novel contribution of utilizing physiological data in addition to psychological measures. High-frequency sampling and combination of psychological and physiological data addresses a crucial gap in the research of stress. This study contributes valuable knowledge to the field of psychophysiology and has implications for expedition planners, research organizations, teams in action settings, pandemic prevention protocols, global crises, and long-duration spaceflight missions. Comprehensive insights promote the well-being and success of individuals in extreme conditions.

Estimation bias and agreement limits between two common self-report methods of habitual sleep duration in epidemiological surveys

Accurate measurement of habitual sleep duration (HSD) is crucial for understanding the relationship between sleep and health. This study aimed to assess the bias and agreement limits between two commonly used short HSD self-report methods, considering sleep quality (SQ) and social jetlag (SJL) as potential predictors of bias. Data from 10,268 participants in the International COVID Sleep Study-II (ICOSS-II) were used. Method-Self and Method-MCTQ were compared. Method-Self involved a single question about average nightly sleep duration (HSDself), while Method-MCTQ estimated HSD from reported sleep times on workdays (HSDMCTQwork) and free days (HSDMCTQfree). Sleep quality was evaluated using a Likert scale and the Insomnia Severity Index (ISI) to explore its influence on estimation bias. HSDself was on average 42.41 ± 67.42 min lower than HSDMCTQweek, with an agreement range within ± 133 min. The bias and agreement range between methods increased with poorer SQ. HSDMCTQwork showed less bias and better agreement with HSDself compared to HSDMCTQfree. Sleep duration irregularity was - 43.35 ± 78.26 min on average. Subjective sleep quality predicted a significant proportion of variance in HSDself and estimation bias. The two methods showed very poor agreement and a significant systematic bias, both worsening with poorer SQ. Method-MCTQ considered sleep intervals without adjusting for SQ issues such as wakefulness after sleep onset but accounted for sleep irregularity and sleeping in on free days, while Method-Self reflected respondents' interpretation of their sleep, focusing on their sleep on workdays. Including an SQ-related question in surveys may help bidirectionally adjust the possible bias and enhance the accuracy of sleep-health studies.

Sleep and cardiometabolic risk. Narrative revision

OBJECTIVES

Sleep disturbances, including disrupted sleep and short sleep duration, are highly prevalent and are prospectively associated with an increased risk for various chronic diseases, including cardiometabolic, neurodegenerative, and autoimmune diseases.

MATERIAL AND METHODS

This is a narrative review of the literature based on numerous articles published in peer-reviewed journals since the beginning of this century.

RESULTS

The relationship between sleep disorders and metabolic dysregulation has been clearly established, mainly in the setting of modern epidemic of cardiometabolic disease, a cluster of conditions include obesity, insulin resistance, arterial hypertension, and dyslipidaemia, all of them considered as main risk factor for atherosclerotic cardiovascular disease (ACVD) and its clinical expression such as ischemic ictus, myocardial infarction and type 2 diabetes. Clinically viable tools to measure sleep duration and quality are needed for routine screening and intervention.

CONCLUSIONS

In view of what has been exposed in this review, it is evident that the timing, amount, and quality of sleep are critical to reduce the burden of risk factors for several chronic disease, including ACVD and type 2 diabetes, and most relevant in young people. Future research studies should elucidate the effectiveness of multimodal interventions to counteract the risk of short sleep for optimal patient outcomes across the healthcare continuum, especially in young people.

Poor sleep is associated with deficits of attention in COPD patients

BACKGROUND

Poor sleep and attention deficits are common in COPD.

OBJECTIVES

To assess the relationship between self-reported poor sleep and attention deficits in COPD. We also studied the association between self-reported sleep and the attention tests with the objective characteristics of sleep.

METHODS

Fifty-nine COPD patients were prospectively studied. Self-reported sleep quality was assessed using the Pittsburgh sleep quality index (PSQI). Objective characteristics of sleep were assessed by actigraphy and polysomnography. Attention was evaluated with the Oxford sleep resistance test (OSLER) and the Psychomotor vigilance test (PVT).

RESULTS

28 (47 %) patients referred poor sleep (PSQI >5). In the OSLER test they showed earlier sleep onset than patients with good sleep, median (Interquartil range): 31.2 min (25.4-40) vs 40 min (28.5-40), p: 0.048. They also spent more time making errors: 4.5 % (0.6-7.6) of total test time vs 0.7 % (0.2-5.3), p: 0.048. In PVT, patients with poor sleep presented a greater dispersion of the reaction time values with a higher value in the slowest 10 % of the reactions, 828 (609-1667) msec. vs 708 (601-993) msec, p: 0.028. No association was found between self-reported poor sleep and objective sleep variables. We found no correlation between OSLER and PVT results and polysomnographic variables except between sleep efficiency and PVT response speed (β: 0.309, p: 0.018).

CONCLUSION

Self-reported poor sleep in COPD is associated with attention deficits. Sleep quality should be included in future studies of this facet of cognition in COPD, as well as to assess its potential usefulness as a therapeutic target.

Poor sleep quality, COPD severity and survival according to CASIS and Pittsburgh questionnaires

Poor sleep quality is frequent among COPD patients and it has been related to worse outcomes. The objective of this study was to compare the COPD and Asthma Sleep Impact Scale (CASIS) and the generic Pittsburgh Sleep Quality Index (PSQI) questionnaires as reliable tools for evaluating sleep quality and its relationship with COPD characteristics and survival. Stable COPD patients were prospectively evaluated. Anthropometric, sociodemographic, comorbidity, lung function and treatment data were collected. All patients completed CASIS and PSQI, mMRC dyspnea severity scale, COPD Assessment Test (CAT), sleep apnoea STOP-Bang and Hospital Anxiety and Depression Scale (HADS) questionnaires. Body mass index, airflow Obstruction, Dyspnea and Exacerbations (BODEx) index was calculated. Life status was determined after a mean follow-up of 3.7 (SD 1) years. We included 200 patients, 69.5% male, mean age 65.8 (9) years. Poor sleep was detected in 100 (50%) and 84 patients (42%) according to PSQI and CASIS questionnaires, respectively, with an agreement of 63%. Poor sleep was related to female gender, more severe dyspnea and worse BODEx, HADS and CAT scores according to both questionnaires. PSQI was associated to chronic pain or inferior urinary tract symptoms and CASIS to exacerbations, shorter walked distance in the 6-min walking test and treatment with oral corticosteroids or chronic oxygen. Thirty nine (19.5%) patients died during follow-up. Mortality was not associated to PSQI nor CASIS results. Unlike PSQI, CASIS is more related to COPD severity and its results are not influenced by comorbidities with known impact on sleep quality. In our sample, poor sleep quality was not associated with increased mortality.

Large muscle group movements during sleep in healthy people: normative values and correlation to sleep features

STUDY OBJECTIVES

To investigate the frequency and characteristics of large muscle group movements (LMMs) during sleep in healthy adults.

METHODS

LMMs were scored following the International Restless Legs Syndrome Study Group criteria in 100 healthy participants aged 19-77 years. A LMM was defined as a temporally overlapping increase in EMG activity and/or the occurrence of movement artifacts in at least two channels. LMM indices and durations in total sleep time (TST), NREM and REM sleep, and association with arousals, awakenings, and/or respiratory events were calculated. Correlations of LMMs indices and durations with sleep architecture, respiratory and motor events, and subjective sleep quality were investigated.

RESULTS

Median LMMs index in TST was 6.8/h (interquartile range (IQR), 4.5-10.8/h), median mean duration 12.4 s (IQR 10.7-14.4 s). Mean LMMs duration was longer in NREM (median 12.7 s, IQR 11.1-15.2 s) versus REM sleep (median 10.3 s, IQR 8.0-13.5s), p < 0.001. LMMs associated with awakening increased with age (p = 0.029). LMMs indices in TST were higher in men than women (p = 0.018). LMMs indices correlated positively with N1 sleep percentage (ρ = 0.49, p < 0.001), arousal index (ρ = 0.40, p = 0.002), sleep stages shift index (ρ = 0.43, p < 0.001, apnea index (ρ = 0.36, p = 0.017), and video-visible movements indices (ρ = 0.45, p < 0.001), and negatively with N3 sleep (ρ = -0.38, p= 0.004) percentage.

CONCLUSIONS

This is the first study providing normative data on LMMs frequency in healthy adults. LMMs are a ubiquitous phenomenon often associated with other events. Correlation with arousals and respiratory events suggests a potential clinical significance of LMMs in adults that awaits further investigation.

The Underlying Mechanisms of Sleep Deprivation Exacerbating Neuropathic Pain

Pain disrupts sleep, and sleep deprivation or interference can alter pain perception in animals and humans, for example by increasing sensitivity to pain. However, the mechanism by which sleep affects neuropathic pain remains unclear. In this review, we discuss the available evidence from the epidemiologic, clinical, and human, as well as laboratory studies. In previous studies, we have found that sleep deprivation affects various injurious systems, including opioids, dopaminergic, immune, orexins, hypothalamic-pituitary-adrenal axis, and adenosine. At the same time, these systems play a crucial role in neuropathic pain regulation. In the complex interactions between these neurobiological systems, there may be potential regulatory pathways through which sleep deprivation amplifies neuropathic pain. Because of the impact sleep problems and neuropathic pain can have on the patients' quality of life, studying the link between sleep and neuropathic pain is important for neuropathic pain prevention and public health.

Identification of Sleep Patterns via Clustering of Hypnodensities

Sleep patterns vary widely between individuals. We explore methods for identifying populations exhibiting similar sleep patterns in an automated fashion using polysomnography data. Our novel approach applies unsupervised machine learning algorithms to hypnodensities graphs generated by a pre-trained neural network. In a population of 100 subjects we identify two stable clusters whose characteristics we visualize graphically and through estimates of total sleep time. We also find that the hypnodensity representation of the sleep stages produces more robust clustering results than the same methods applied to traditional hypnograms.

Subjective sleep assessments are correlated with EEG-related sleep measurements of the first sleep cycle in healthy young adults

This study examined whether subjective and objective sleep parameters (sleep stage, electroencephalography [EEG] power, heart rate variability) are related to the progression of sleep cycles using differences in the variables between two nights. We hypothesized that the association between night-to-night differences between subjective and objective sleep variables reflect the difference in objective sleep variables in the first sleep cycle. Seventy-seven healthy adults (23.8 ± 2.2 years; 41 females) participated in polysomnographic recordings on two consecutive nights. To extract the variables that represent the difference between the nights, the sleep parameters of Night 1 were subtracted from those of Night 2. Spearman's rho was used to assess correlations between subjective sleep assessments and objective sleep parameters, with false discovery rate correction for multiple comparisons. Subjective sleep assessments were significantly correlated with whole-night sleep architecture and quantitative EEG activity, but not with heart rate variability during the night. Among sleep cycles, subjective sleep parameters were correlated with the objective sleep parameters in the first sleep cycle ("Ease of falling asleep" vs. waking after sleep onset [r = - 0.382], "Depth of sleep" vs. EEG theta power [r = 0.404], "Quality of sleep" vs. the percentage of stage N3 [r = 0.412] and EEG delta power [r = 0.458], all p < 0.05). These results suggest the importance of taking the difference among the nights into account when assessing subjective sleep quality. This study clarified that sleep in the first sleep cycle has a dominant influence on subjective sleep assessments.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41105-022-00437-x.

Recent Progress in Long-Term Sleep Monitoring Technology

Sleep is an essential physiological activity, accounting for about one-third of our lives, which significantly impacts our memory, mood, health, and children's growth. Especially after the COVID-19 epidemic, sleep health issues have attracted more attention. In recent years, with the development of wearable electronic devices, there have been more and more studies, products, or solutions related to sleep monitoring. Many mature technologies, such as polysomnography, have been applied to clinical practice. However, it is urgent to develop wearable or non-contacting electronic devices suitable for household continuous sleep monitoring. This paper first introduces the basic knowledge of sleep and the significance of sleep monitoring. Then, according to the types of physiological signals monitored, this paper describes the research progress of bioelectrical signals, biomechanical signals, and biochemical signals used for sleep monitoring. However, it is not ideal to monitor the sleep quality for the whole night based on only one signal. Therefore, this paper reviews the research on multi-signal monitoring and introduces systematic sleep monitoring schemes. Finally, a conclusion and discussion of sleep monitoring are presented to propose potential future directions and prospects for sleep monitoring.

Effects of non-pharmacological interventions on sleep in chronic low back pain: A systematic review and meta-analysis of randomised controlled trials

Low back pain is a leading cause of disability worldwide and adults with chronic low back pain (≥12weeks) commonly experience sleep impairments (e.g., insomnia, sleep disturbance). This study examined the effects of non-pharmacological interventions on sleep in adults with chronic low back pain. Six databases (PubMed, CINAHL, SPORTDiscus, PsycINFO, EMBASE, CENTRAL) were searched from inception to 2 June 2021 for randomised controlled trials. Pairwise random-effect meta-analysis estimated standardised mean difference (Hedges' g) at end-of-intervention follow-up. Nineteen studies (participants: 1348) were included. When compared to control, non-pharmacological interventions improved sleep (g [95%CI]: -0.33 [-0.56, -0.11], p = 0.004, small effect, I² = 59.3%; n = 879; studies: n = 13; GRADE: low). This small improvement in sleep was associated with a moderate reduction in pain intensity (-0.69 [-1.00, -0.38], p < 0.001, I² = 75.3%; n = 812; studies: n = 12; GRADE: very low) and no changes in back-related disability (-0.50 [-1.13, 0.14], p = 0.129, I² = 91.4%; n = 517; studies: n = 6; GRADE: low). Notably, all eligible studies reported interventions primarily aimed to reduce pain, although our search criteria were not limited to pain interventions. Key limitations were data paucity and high risk of bias. Future research should investigate sleep-based interventions (i.e., those purposely designed to improve sleep) using subjective and objective measures across a range of sleep domains (CRD42021275227).

Method to quantify the impact of sleep on cardiac neuroautonomic functionality: application to the prediction of cardiovascular events in the Multi-Ethnic Study of Atherosclerosis

We introduce the concept of cardiac neuroautonomic renewability and a method for its quantification. This concept refers to the involuntary nervous system's capacity to improve cardiac control in response to restorative interventions, such as sleep. We used the change in heart rate fragmentation (ΔHRF), before sleep onset compared with after sleep termination, to quantify the restorative effects of sleep. We hypothesized that the ability to improve cardiac neuroautonomic functionality would diminish with age and be associated with lower risk of major adverse cardiovascular events (MACE). We analyzed the ECG channel of polysomnographic recordings from an ancillary investigation of the Multi-Ethnic Study of Atherosclerosis (MESA). In a cohort of 659 participants (mean ± SD age, 69.7 ± 8.8; 42% male), HRF was significantly (P < 0.001) lower after sleep (before: 74 ± 12%, after: 67 ± 13%). Furthermore, the magnitude of the decrease significantly (P < 0.001) diminished with cross-sectional age. In addition, a larger reduction in HRF following sleep (i.e., higher ΔHRF) was associated with lower risk of MACE, independent of traditional cardiovascular risk factors and current measures of sleep quality. Specifically, over a mean follow-up period of 6.4 ± 1.6 yr, in which 60 participants had their first MACE, a one-SD (12%) increase in ΔHRF was associated with a 36% (95% CI: 12%-53%) decrease in the risk of MACE. The results demonstrate the restorative impact of sleep on heart rate control. As such they support the concept of cardiac neuroautonomic renewability and the utility of ΔHRF for its quantification.