Sympathetic-nerve activity during sleep in normal subjects

Slumber under pressure: REM sleep and stress response

Sleep, a state of reduced responsiveness and distinct brain activity, is crucial across the animal kingdom. This review explores the potential adaptive functions of REM sleep in adapting to stress, emphasizing its role in memory consolidation, emotional regulation, and threat processing. We further explore the underlying neural mechanisms linking stress responses to REM sleep. By synthesizing current findings, we propose that REM sleep allows animals to "rehearse" or simulate responses to danger in a secure, offline state, while also maintaining emotional balance. Environmental factors, such as predation risk and social dynamics, further influence REM sleep. This modulation may enhance survival by optimizing stress responses while fulfilling physiological needs in animals. Insights into REM sleep's role in animals may shed light on human sleep in the context of modern stressors and sleep disruptions. This review also explores the complex interplay between stress, immunity, sleep disruptions-particularly involving REM sleep-and their evolutionary underpinnings.

Actigraphy-based sleep disruption and diurnal biomarkers of autonomic function in paroxysmal atrial fibrillation

INTRODUCTION

Sleep architectural disruption is associated with atrial fibrillation (AF); however, associated autonomic influences remain unclear and it is unknown if this detriment persists during wakefulness. We hypothesize sleep disruption and autonomic dysfunction have diurnal patterning in patients with paroxysmal AF.

METHODS

We analyzed data from the Sleep Apnea and Atrial Fibrillation Biomarkers and Electrophysiologic Atrial Triggers (SAFEBEAT) study designed to examine paroxysmal AF and sleep apnea, including simultaneous collection of continuous electrocardiogram monitoring (Heartrak Telemetry®) and actigraphy (Actiwatch GTX) for 7-21 days. Heart rate variability (HRV) measures in time-domain (standard deviation of normal-to-normal (NN) intervals (SDNN), coefficient of variation (CV)) and frequency-domain (low frequency power (LFP), high frequency power (HFP)) were used as surrogates of autonomic function and averaged per sleep/wake per day. A linear mixed-effects model assuming compound symmetry correlation structure was used to assess the relationship of HRV with actigraphy-derived sleep data.

RESULTS

The analytic sample (age 60.1 ± 12.0 years, body mass index 32.6 ± 6.7 kg/m2, 36% female, 75% White) included 100 participants with paroxysmal AF. Longer sleep latency was associated with lower HFP during wakefulness (coefficient - 0.0501, p = 0.031). Higher sleep efficiency was associated with increased SDNN (coefficient 0.0007, p = 0.014) and CV (coefficient 0.0167, p = 0.047). Higher arousal index was associated with increased CV (coefficient 0.0166, p = 0.007) and LFP (coefficient 0.0232, p = 0.003). During sleep, longer average awakenings duration was associated with increased LFP/HFP ratio (coefficient 0.1977, p < 0.001) and reduced HFP (coefficient - 0.1338, p < 0.001). Significant sleep-wake interactions were observed for sleep latency with HFP (p = 0.024), sleep efficiency with SDNN and CV (both p < 0.01), WASO with SDNN, CV, and LFP (all p < 0.05), and frequency of awakenings with CV and LFP (both p < 0.05).

CONCLUSIONS

Actigraphy-based measures of sleep disruption were associated with autonomic function alterations exhibiting diurnal variability in paroxysmal AF. Greater overall HRV and parasympathetic modulation were related to better sleep quality. Increased sympathetic activation was associated with sleep fragmentation. Results provide insights into differential autonomic dysfunction related to sleep disruption that may contribute to atrial arrhythmogenesis.

Pathophysiology of Urethral Instability: Dysfunction of Smooth Urethral Musculature

AIMS

The aim of this study is to elucidate the pathophysiological mechanisms of urethral instability by analyzing and comparing cystometric data from a female individual with urethral instability and another with normal micturition.

METHODS

Data were collected from a previous study measuring urethral pressure at three distinct points within the urethra, along with continuous needle electromyography (EMG) recordings of the external striated urethral sphincter. A comprehensive literature review on the function of different urethral muscle groups was also conducted to support the findings.

RESULTS

The findings suggest that urethral instability primarily results from a loss of smooth muscle closure function. This condition is triggered by the interaction of pre-existing high urethral tension and low-level vesical afferent firing at the onset of bladder filling, causing relaxation of the urethral smooth musculature and impaired closure function of the urethra. The subsequent entry of fluid into the proximal urethra induces reflex contractions of the external sphincter, in an attempt to close the urethra and prevent urine loss and manifests as urethral instability. Compared to normal micturition, which shows a gradual decline in urethral pressure, the subject with instability exhibited rapid fluctuations in urethral pressure and EMG activity.

CONCLUSIONS

This study highlights the role of smooth urethral musculature in maintaining urethral closure function during bladder filling. Therapeutic approaches should focus on reducing basal urethral tension to preserve smooth muscle closure function during bladder filling. Future research may explore pharmacological interventions, particularly adrenergic beta-3 receptor agonists or alpha blockers, as potential treatments for urethral instability.

Sleep stage, sleep fragmentation and heart rate variability during the initial 3-h sleep period in patients with obstructive sleep apnea syndrome

To investigate differences in polysomnography (PSG) parameters and heart rate variability (HRV) during the initial 3-h sleep period in patients with mild, moderate, and severe obstructive sleep apnea syndrome (OSA). According to the apnea-hypopnea index, patients were divided into 3 groups: mild, moderate, and severe (n = 23, 59, and 94, respectively). PSG was performed, and HRV (frequency domain analysis), sleep stage (S1, S2, S3, REM, and waking), and sleep fragmentation index (SFI) were measured during the initial 3-h sleep periods. The total S1 time was significantly longer in the severe group than in the mild and moderate groups (p < 0.001). The severe group had significantly shorter total S2 and S3 times than the mild (p = 0.014, p < 0.001) and moderate (p = 0.034, p = 0.029) groups did. The SFI was significantly greater in the severe group than in the mild and moderate groups (p < 0.001, p = 0.008). The high-frequency component (HF) of the HRV showed no significant differences except that it was significantly smaller during S3 in the moderate group than in the mild group (p = 0.026). Compared with those with mild/moderate status, patients with severe OSA have shallower sleep and a higher SFI, suggesting poorer sleep quality. Although HF during S3 was significantly smaller in the moderate group, it did not significantly differ between the mild and severe groups, suggesting that the parasympathetic nervous system might compensate for humoral and hypoxemic abnormalities in patients with severe OSA.

A perspective on automated rapid eye movement sleep assessment

Rapid eye movement sleep is associated with distinct changes in various biomedical signals that can be easily captured during sleep, lending themselves to automated sleep staging using machine learning systems. Here, we provide a perspective on the critical characteristics of biomedical signals associated with rapid eye movement sleep and how they can be exploited for automated sleep assessment. We summarise key historical developments in automated sleep staging systems, having now achieved classification accuracy on par with human expert scorers and their role in the clinical setting. We also discuss rapid eye movement sleep assessment with consumer sleep trackers and its potential for unprecedented sleep assessment on a global scale. We conclude by providing a future outlook of computerised rapid eye movement sleep assessment and the role AI systems may play.

Sleep and cardiac autonomic modulation in older adults: Insights from an at-home study with auditory deep sleep stimulation

The autonomic nervous system regulates cardiovascular activity during sleep, likely impacting cardiovascular health. Aging, a primary cardiovascular risk factor, is associated with cardiac autonomic disbalance and diminished sleep slow waves. Therefore, slow waves may be linked to aging, autonomic activity and cardiovascular health. However, it is unclear how sleep and slow waves are linked to cardiac autonomic profiles across multiple nights in older adults. We conducted a randomized, crossover trial involving healthy adults aged 62-78 years. Across 2 weeks, we applied auditory stimulation to enhance slow waves and compared it with a SHAM period. We measured sleep parameters using polysomnography and derived heart rate, heart rate variability approximating parasympathetic activity, and blood pulse wave approximating sympathetic activity from a wearable. Here, we report the results of 14 out of 33 enrolled participants, and show that heart rate, heart rate variability and blood pulse wave within sleep stages differ between the first and second half of sleep. Furthermore, baseline slow-wave activity was related to cardiac autonomic activity profiles during sleep. Moreover, we found auditory stimulation to reduce heart rate variability, while heart rate and blood pulse wave remained unchanged. Lastly, within subjects, higher heart rate coincided with increased slow-wave activity, indicating enhanced autonomic activation when slow waves are pronounced. Our study shows the potential of cardiac autonomic markers to offer insights into participants' baseline slow-wave activity when recorded over multiple nights. Furthermore, we highlight that averaging cardiac autonomic parameters across a night may potentially mask dynamic effects of auditory stimulation, potentially playing a role in maintaining a healthy cardiovascular system.

Polysomnographic characteristics of patients with heart failure combined with sleep apnea: A systematic review and meta-analysis

AIMS

Objective sleep parameters in patients with HF and their comorbidity with sleep-disordered breathing (SDB) are not fully understood. We aimed to investigate the polysomnography-measured sleep characteristics in HF patients using a systematic review and meta-analysis.

METHODS

PubMed, Embase, and Web of Science databases were searched for studies on PSG in HF patients. Meta-analyses were conducted to compare PSG parameters between HF patients and Non-HF, HF patients with and without SDB, HF patients with different types of SDB, and HF patients before and after SDB treatments.

RESULTS

HF patients showed decreased sleep efficiency (MD = -7.5 %, 95 %CI: [-10.8 %, -4.1 %], P < 0.001) and reduced slow wave sleep (MD = -3.2 %, 95 %CI: [-5.7 %, -0.7 %], P = 0.013) compared with those without HF. With comorbid SDB, HF patients experienced further decreases in sleep efficiency and total sleep time, and disruptions in sleep architecture, including decreased rapid-eye-movement sleep (MD = -3.4 %, 95 %CI: [-6.2 %, -0.5 %], P = 0.020) and SWS (MD = -3.1 %, 95 %CI: [-4.1 %, -2.1 %], P < 0.001).

CONCLUSIONS

HF patients showed poorer sleep continuity and less restorative sleep. Additionally, SDB was associated with poor objective sleep architecture in HF patients, indicated by a decrease in the percentage of deep sleep and an increase in sleep fragmentation. SDB treatments, such as adaptive servo-ventilation (ASV) and continuous positive airway pressure (CPAP), were associated with improved sleep quality and quantity in HF patients with SDB.

Obese Hypertensive Men Have Fasting Serum Concentrations of Leptin Similar to Those of Obese Normotensive Men

BACKGROUND

Leptin is a hormone that is secreted by the adipocytes. In the circulation, leptin levels are directly proportional to the body fat percentage. Studies have shown that higher leptin levels are associated with an increased risk of hypertension after adjusting for body mass index (BMI). Therefore, leptin has been proposed as a mediator of obesity-related hypertension. Whether leptin is associated with hypertension when controlling for body fat percentage remains unclear.

METHODS

We studied 103 obese men (BMI ≥ 30.0 kg/m2). All men were healthy and were medication-free. We measured blood pressure using 24-h ambulatory blood pressure (ABP) recordings. Hypertension was defined as 24-h systolic ABP ≥ 130 mm Hg and/or 24-h diastolic ABP ≥ 80 mm Hg, and normotension was defined as 24-h ABP < 130/80 mm Hg. We measured fasting serum leptin concentrations and used dual-energy X-ray absorptiometry scanning to determine body fat percentage.

RESULTS

Of the 103 obese men, 64 were hypertensive (24-h systolic ABP-mean ± standard deviation-137 ± 11 mg Hg and 24-h diastolic ABP 83 ± 6 mm Hg) and 40 were normotensive (24-h systolic ABP 117 ± 6 mg Hg and 24-h diastolic ABP 73 ± 4 mm Hg). The 2 groups had similar fasting serum leptin concentrations (median-interquartile range; 13.4 (5.7-36.1) µg/L vs. 13.4 (5.4-27.1) µg/L, P = 0.88) and total fat mass percentage (34.8 ± 4.5% vs. 34.0 ± 4.7%, P = 0.90).

CONCLUSIONS

Obese hypertensive men have serum leptin concentrations similar to those of obese normotensive men with comparable body fat percentage measurements. This finding does not support leptin's candidacy as a mediator of obesity-related hypertension.

Do Sleep Time and Duration Affect the Development of Prehypertension in Undergraduate Medical Students? An Experience from a Tertiary Care Hospital in Kolkata

Introduction and Objective  Hypertension is an evolving public health challenge at present, and it is preceded by a prehypertensive stage. Irregular sleep duration and pattern have been found to be linked with cardiovascular diseases. Medical students are highly vulnerable to low quality sleep due to pressure regarding the academic curriculum and poor lifestyle. The present study aimed to estimate the prevalence of prehypertension, describe the risk factors and sleep patterns of undergraduate medical students, and determine the association, if any, involving sleep time and duration and prehypertension. Materials and Methods  Data was collected from 254 undergraduate medical students via the Pittsburgh Sleep Quality Index (PSQI) questionnaire and a self-structured questionnaire. The frequency of events was established and the Chi-squared and t -tests were applied to determine the association. Finally, regression analysis was performed to determine the correlation. Results  Male sex, high body mass index (BMI), poor sleep quality, and night sleep duration shorter than 5 hours were found to be significant risk factors for the development of prehypertensive condition (prevalence of 42.5%). However, there were no statistically significant associations regarding prehypertension and family history, junk food and salt intake, physical activity and daytime napping, bedtime, and wake-up time. Night sleep duration shorter than 5 hours presented an odds ratio of 4.713 ( p  = 0.010) for the development of prehypertension after adjusting for other risk factors, such as male sex, sleep quality, and high BMI. Discussion and Conclusion  A high prevalence of prehypertension (42.5%) was noted among undergraduate medical students. Night sleep duration shorter than 5 hours was a significant risk factor for the development of prehypertension, whereas sleep time was not significantly associated with prehypertension.

Clinical neurocardiology: defining the value of neuroscience-based cardiovascular therapeutics - 2024 update

The intricate role of the autonomic nervous system (ANS) in regulating cardiac physiology has long been recognized. Aberrant function of the ANS is central to the pathophysiology of cardiovascular diseases. It stands to reason, therefore, that neuroscience-based cardiovascular therapeutics hold great promise in the treatment of cardiovascular diseases in humans. A decade after the inaugural edition, this White Paper reviews the current state of understanding of human cardiac neuroanatomy, neurophysiology and pathophysiology in specific disease conditions, autonomic testing, risk stratification, and neuromodulatory strategies to mitigate the progression of cardiovascular diseases.

Future of Sleep Medicine: Novel Approaches and Measures Derived from Physiologic Systems Dynamics (Part I)

We review recent progress in understanding fundamental aspects of physiologic regulation during wake and sleep based on modern data-driven, analytical, and computational approaches with a focus on the complex dynamics of individual physiologic systems. The presented empirical findings indicate that sleep-wake and circadian cycles do not simply modulate basic physiologic functions but influence physiologic systems dynamics simultaneously over a broad range of time scales. The reviewed empirical approaches and derived measures represent novel mechanistic aspects of sleep and wake regulation, and lay the foundation for a new class of diagnostic and prognostic biomarkers in clinical sleep medicine.

Brain Health in Sleep Disorders

Sleep is a critical determinant of brain health, influencing cognitive, emotional, and physiologic functions. The complex bidirectional relationship between sleep and brain health underscores the importance of sleep in maintaining cognitive function, regulating brain homeostasis, and facilitating the clearance of metabolic waste through the glymphatic system. Chronic sleep deprivation and sleep disorders such as insomnia and obstructive sleep apnea have been shown to negatively impact brain structures and functions. This review discusses the impact of sleep disorders on brain health. It also explores the implications of impaired sleep on cardiovascular health, immune function, and neuroplasticity.

The Influence of Commonly-Encountered Participant Behaviors on Cardiovascular Indices During Testing

BACKGROUND

During laboratory testing, participants rest quietly in a supine posture with little movement. However, it is rather common for participants to display various behaviors. The extent to which these common encounters influence cardiovascular measures is unknown.

METHODS

Fifty-five adults (36 ± 15 years) were studied during the following seven randomized conditions in the supine position: (i) quiet stationary rest (control), (ii) while drowsy, (iii) while and (iv) after talking to investigators, (v) while and (vi) after cell phone use for texting, and (vii) lying on the side.

RESULTS

Heart rate was greater when the participants were talking to investigators (+4 bpm) and texting on cell phones (+5 mm Hg) compared with quiet rest. Systolic blood pressure (BP) increased by 4 mm Hg and diastolic BP by 3 mm Hg while talking to investigators. Systolic BP was 6 mm Hg and diastolic BP was 5 mm Hg lower in the "side lying" position compared with quiet rest. In the side-lying condition, carotid-femoral pulse wave velocity (PWV) was not able to be measured in 38% (n = 16) of the participants while brachial-ankle PWV was not affected. Brachial-ankle PWV was greater while (+65 cm/s) and after (+29 cm/s) the participants were talking to investigators whereas carotid-femoral PWV was not able to be measured during talking. The drowsy behavior did not influence any of the BP and PWV measures.

CONCLUSIONS

Talking during the testing period significantly increases all the cardiovascular measures but cell phone use prior to the measures does not appear to influence them.

The interaction between comorbidities and sleep stages influences oxygen re-saturation characteristics

Sleep stages exhibit differing patterns of cardiac, respiratory and nervous system activation. Rapid eye movement (REM) sleep is associated with deeper oxygen desaturation events in obstructive sleep apnea. However, no studies have looked to the effect of sleep staging on re-saturation characteristics. Polysomnographic data from the Sleep Heart Health Study were utilised to derive oxygen saturation parameters from events having both desaturation and re-saturation parts. Sleep stages were described as non-REM (NREM) 1 or 2 (combined), 3 and REM. Sleep stage effects on desaturation and re-saturation characteristics were investigated in a healthy subgroup (n = 759) and participants with hypertension (n = 2534), lung disease (n = 715), heart failure (n = 199) and myocardial infarction (n = 713). A total of 3793 participants (48.3% female) were included for analysis (171,976 saturation events; median 20 per participant). Events during REM had the longest duration, deepest nadirs and greatest area for desaturations and re-saturations. Sleep stage effected re-saturation parameters more than desaturation parameters, with a relative difference from NREM 1/2 to REM in duration of 16.7% and 29.8%, in rate of 0.2% and 4.5% and in area of 36.1% and 48.0% for desaturation and re-saturation, respectively, among healthy participants. Similarly, the effect of comorbidities was greater upon re-saturations than desaturations, as participants with heart failure recorded a relative difference to healthy participants of 10.3% and 24.4% for desaturation and re-saturation duration, respectively, 12.8% and 15.0% for rate and 6.4% and 16.4% for area. Sleep stages and comorbidities have significant effects upon nocturnal oxygen re-saturation parameters. Cardiorespiratory comorbidities elicit greater degradations in oxygen re-saturations than they do desaturations.

Association of Obstructive Sleep Apnea and Nocturnal Hypoxemia With the Circadian Rhythm of Myocardial Infarction

BACKGROUND

The circadian rhythm of myocardial infarction (MI) in patients with obstructive sleep apnea (OSA) remains disputable and no studies have directly evaluated the relationship between nocturnal hypoxemia and the circadian rhythm of MI. The aim of the current study was to evaluate the association of OSA and nocturnal hypoxemia with MI onset during the night.

METHODS

Patients with MI in the OSA-acute coronary syndrome (ACS) project (NCT03362385) were recruited. The time of MI onset was identified by patient's report of the chest pain that prompted hospital admission. All patients underwent an overnight sleep study using a type III portable sleep monitoring device after clinical stabilization during hospitalization. The difference in circadian variation of MI onset was evaluated between patients with moderate/severe OSA and non/mild OSA and those with or without nocturnal hypoxemia. Nocturnal hypoxemia was evaluated using 3 variables, including oxygen desaturation index, minimum oxygen saturation, and total sleep time with saturation <90%.

RESULTS

Among 713 patients enrolled, 398 (55.8%) had moderate/severe OSA (apnea-hypopnea index ≥15 events·h - 1). Compared with the non/mild OSA group, the MI onset was significantly increased in the moderate/severe OSA group between midnight to 5:59 am in 6-hour epochs analysis (26.9% versus 18.4%, P=0.008). Only in patients with both moderate/severe OSA and nocturnal hypoxemia, including oxygen desaturation index ≥15, minimum oxygen saturation ≤86%, and total sleep time with saturation <90% ≥2%, the incidence of MI onset between midnight to 5:59 am was significantly increased. Moderate/severe OSA (adjusted odds ratio 1.66 [95% CI, 1.13-2.43]; P=0.01) and nocturnal hypoxemia (oxygen desaturation index ≥15 model, adjusted odds ratio 1.80, [95% CI, 1.21-2.66]; minimum oxygen saturation ≤86% model, adjusted odds ratio 1.70 [95% CI, 1.16-2.47]; P=0.006; total sleep time with saturation <90% ≥2% model, adjusted odds ratio 1.54 [95% CI, 1.04-2.27]; P=0.03) significantly predicted MI occurrence from midnight to 6:00 am.

CONCLUSIONS

A peak of incident MI onset between midnight to 5:59 am was observed in patients with moderate/severe OSA, especially in those presenting with nocturnal hypoxemia.

Modulation of cardiac autonomic activity across consciousness states and levels of sleep depth in individuals with sleep complaints and bipolar disorder or unipolar depressive disorders

OBJECTIVE

Autonomic nervous system dysfunction and reduced heart rate variability (HRV) often co-exist with mood disorders, a phenomenon likely influenced by sleep disturbances. This study investigated heart rate (HR) and HRV across wake, rapid eye movement (REM) sleep, and non-REM (NREM) sleep in individuals with sleep complaints and bipolar or unipolar depressive disorder.

METHODS

Polysomnographic data was retrospectively collated for 120 adult patients with sleep complaints and depressive symptoms [60 diagnosed with bipolar disorder, 60 diagnosed with a unipolar depressive disorder], and 60 healthy controls. HR and time-based HRV variables were computed on 30-s segments and averaged across the night for wake, NREM and REM sleep.

RESULTS

Significant group by consciousness state interactions showed that the unipolar and bipolar groups had lower standard deviation of normal-to-normal intervals root mean square of successive R-R interval differences compared to controls during NREM and REM sleep, but not during wake (SDNN: F(4, 330) = 3.0, p = .021, np2 = 0.035; RMSSD: F(4, 332) = 5.8, p < .001, np2 = 0.065). The magnitude of these group differences did not vary significantly between NREM 1, NREM 2 and NREM 3 sleep. These interactions persisted after excluding individuals taking 3rd generation antipsychotic, lithium, anticonvulsant, and cardiovascular medications.

CONCLUSION

Although further work is required to account for the impact of psychotropic and cardiac medications, as well as manic and euthymic states, these findings suggest that the sleep-based autonomic signature of depressive states differs across different types of mood disorders and could potentially inform the development of biomarkers and therapeutic targets.

Association of Novel EEG Biomarkers of Sleep Depth and Cortical Arousability with Cardiac Autonomic Modulation in Adolescents

STUDY OBJECTIVES

To examine the developmental association of the odds ratio product (ORP), an electroencephalographic measure of sleep depth, during non-rapid eye movement (NREM) sleep with 24-hour heart rate variability (HRV), an electrocardiographic measure of cardiac autonomic modulation (CAM), in the transition to adolescence.

METHODS

Leveraging data from the Penn State Child Cohort, we performed longitudinal analyses on 313 children (median [Md] age 9 years) followed-up after Md=7.4y and cross-sectional analyses on 344 adolescents (Md=16y). We extracted ORP during NREM sleep and in the 9 seconds following cortical arousals (ORP-9) from 9-hour, in-lab polysomnography, and frequency- and time-domain HRV indices from 24-h Holter ECG monitoring. Longitudinal and cross-sectional, multivariable-adjusted, regression models examined the association between ORP and ORP-9 with adolescent 24-h HRV indices.

RESULTS

Longitudinally, a greater increase in ORP-9 since childhood was associated with lower daytime Log-LF, SDNN, RMSSD and higher HR in adolescence (p<0.05). A greater increase in ORP since childhood was associated with lower nighttime Log-LF and SDNN (p<0.05). Cross-sectionally, higher ORP and ORP-9 were associated with lower daytime and nighttime Log-LF, SDNN or RMSSD and higher HR within adolescence (p<0.05).

CONCLUSIONS

A greater increase in cortical arousability since childhood is a strong developmental predictor of daytime cardiac autonomic imbalance in adolescence. Shallower sleep depth additionally arises as a proximal determinant of both daytime and nighttime cardiac autonomic imbalance within adolescence. These data suggest a coupling between fine-grained spectral measures of the sleeping brain and those of CAM, which may inform sleep-related cardiovascular risk early in life.

Association between slow wave sleep and blood pressure in insomnia

STUDY OBJECTIVES

The majority of patients with insomnia exhibit abnormal sleep in objective testing (e.g. decreased sleep duration, decreased slow wave sleep [SWS]). Previous studies have suggested that some of these objective measures of poor sleep, such as decreased sleep duration, are associated with a higher risk of hypertension in insomnia. We examined the relationship between SWS and morning and evening blood pressure (BP) levels in patients with clinically diagnosed insomnia.

METHODS

A total of 229 normal sleepers and 1378 insomnia patients were included in this study. Insomnia was defined based on standard diagnostic criteria with symptoms lasting ≥6 months. All participants underwent in-laboratory polysomnography. Patients were classified into quartiles of percent SWS. Evening and morning hypertension were defined using BP measurements taken in the evening before and in the morning after polysomnography, respectively. Multivariable logistic regression models were used to assess the relationship between insomnia, SWS, and hypertension.

RESULTS

Insomniacs with <3.5% SWS (OR 3.27, 95% confidence intervals [CI]: 1.31 to 7.66) and those with 3.5%-10.2% SWS (OR 2.38, 95% CI: 1.28 to 5.91) had significantly greater odds of morning hypertension compared to normal sleepers. No associations were seen in insomnia with 10.2%-15.8% SWS and with >15.8% SWS. Significant effect modifications by sex (p = .043) were found, as decreased SWS was associated with morning hypertension only in men. Odds of evening hypertension were not significantly associated with SWS.

CONCLUSIONS

Decreased SWS is associated with morning hypertension in a dose-dependent manner in insomnia, especially in men.

Influence of alexithymia severity in the healthy population on the susceptibility to false interoceptive feedback

Alexithymia is a psychological trait characterized by difficulty expressing emotions. Previous studies reported that individuals with higher alexithymia have a decreased sense of interoception, which is the sense of monitoring and controlling internal organs. Thus, we hypothesized that internal organ activity (cardiac activities in the present study) was easily affected by false feedback in individuals with severe alexithymia. Therefore, we investigated whether the effects of fake heart rate feedback on real cardiac activities differ depending on the severity of alexithymia as assessed by the 20-item Toronto Alexithymia Scale (TAS-20). Fake heart rate feedback was presented as if it were occurring in the individual's hand through a virtual reality system at various speeds. Changes in cardiac activities were evaluated by the root-mean-square-successive difference (RMSSD, high value indicates greater parasympathetic tone) of the heartbeat interval. Our findings revealed a negative correlation between externally oriented thinking, a subscale of the TAS-20 score, and the RMSSD change ratio elicited by fake heart rate feedback. These findings indicate that individuals with higher alexithymia might be particularly susceptible to external fake feedback.

The effects of morning versus evening high-intensity interval exercise on the magnitude of the morning blood pressure surge

Blood pressure (BP) follows a circadian rhythm, dipping during sleep and surging in the morning. A larger morning BP surge is an independent predictor of cardiovascular events. Acute exercise can produce sustained periods of post-exercise hypotension that last up to 24 h; however, the timing of exercise (morning vs. evening) may influence this response. Whether the timing of exercise influences the morning BP surge remains unknown. The current study investigated the effects of a bout of high-intensity interval exercise (HIIE) performed in the morning versus evening on the magnitude of the morning BP surge in young healthy adults. Twenty-six young, otherwise healthy adults (23 ± 4 years; 15 females) completed a randomized crossover trial where, on different days, they completed a no exercise control visit or performed either morning (0800-1000 h) or evening (1700-1900 h) HIIE. Following each visit, ambulatory BP was assessed in 30 min intervals for 24 hrs. HIIE at either time did not alter the magnitude of the morning BP surge compared to control values (control: 22 ± 5 mmHg; morning exercise: 20 ± 8 mmHg; evening exercise: 22 ± 10 mmHg, P = 0.40) or when grouped separately by sex (visit × sex P = 0.42). A positive correlation existed between Morningness-Eveningness Questionnaire score and the change in nighttime BP following both exercise times (both r = 0.42 and P = 0.04). These findings suggest that HIIE does not attenuate the morning BP surge in young healthy adults and that chronotype can predict nighttime BP responses following HIIE, irrespective of exercise time of day. This study was registered on ClinicalTrials.gov (NCT06702930).

Associations between self-reported sleep duration and incident cardiovascular diseases in a nationwide prospective cohort study of Chinese middle-aged and older adults

Purpose

This study explores the correlation between sleep duration and cardiovascular disease (CVD) among middle-aged and older adults in China. Furthermore, we aim to investigate the association between sleep duration and incident CVD in this population, while assessing potential variations across different age and gender subgroups.

Methods

Utilizing data from the nationwide prospective survey of the China Health and Retirement Longitudinal Study (CHARLS) conducted in 2011, 2013, 2015, and 2018, involving 17,596 participants aged 45 years and above, we employed Cox proportional hazards regression models. These models were used to examine the impact of baseline sleep duration on CVD, considering age (middle-aged/elderly) and gender (male/female) groups.

Results

Over the 8-year follow-up, 2,359 CVD events were recorded. Compared to individuals sleeping 6-8 h per day, a short sleep duration (≤6 h/day) was significantly associated with an increased risk of CVD (HR: 1.17, 95% CI: 1.03-1.33). Subgroup analysis revealed a more pronounced relationship in participants aged ≥60 years, where both short sleep duration (≤6 h/day) (HR: 1.17, 95% CI: 1.02-1.35) and long sleep duration (>8 h/day) (HR: 1.20, 95% CI: 1.02-1.41) were significantly associated with an elevated risk of CVD. Specifically, among female participants, short sleep durations (≤6 h/day) was significantly associated with CVD (HR: 1.24, 95% CI: 1.05-1.47).

Conclusion

Short sleep durations can serve as predictive factors for CVD in China's population aged 45 and above, particularly among elderly female participants. Our study underscores the importance of considering sleep health as a critical aspect when formulating strategies for enhancing CVD prevention.

Stress Reactivity, Wellbeing and Functioning in University Students: A Role for Autonomic Activity During Sleep

Sleep is a key biological mechanism in promoting wellbeing and resilience to stress. This cross-sectional study examined connections between sleep, autonomic function, wellbeing, and stress reactivity in healthy individuals. Demographic, lifestyle, sleep, and psychological well-being information were collected from 85 healthy university students. These variables were analysed in conjunction with indices of cardiac autonomic activity, including heart rate and high frequency heart rate variability (HF HRV, an indicator of parasympathetic vagal tone) recorded during nocturnal sleep onset and in response to a cognitive stressor. Correlational analyses revealed that unrefreshing and fragmented sleep was strongly associated with lower HF HRV at sleep onset, suggestive of poorer autonomic de-arousal. Further, those with minimal increases in HF HRV from wakefulness to sleep reported worse sleep quality and greater challenges in daily activities compared to those with significant increases. This same group also demonstrated significantly greater reactivity and slower recovery when faced with a stressor the next day, as evidenced by comparison of heart rate values. Our findings suggest an association between autonomic hypervigilance and aspects of sleep quality, with potential implications for wellbeing and stress responses.

Nocturia and obstructive sleep apnoea

Nocturia, the need to urinate at night, is a common symptom in patients with obstructive sleep apnoea (OSA). Continuous positive airway pressure treatment can reduce nocturia in some patients, but the underlying mechanisms are complex and not fully understood. OSA affects the autonomic nervous system, oxidative stress and endothelial damage. Furthermore, the commonly held theory attributing polyuria to a false signal of cardiac overload and response natriuresis has limitations. A comprehensive approach to the management of nocturia in OSA, considering factors such as comorbidities, medication use, alcohol consumption and lifestyle, is needed. Effective management of nocturia in OSA requires a multidisciplinary approach, and urologists should be aware of the potential effect of OSA on physiology and refer patients for further testing at a sleep centre. In addition to continuous positive airway pressure, other interventions such as oral appliances and surgical obstruction treatment could be beneficial for some patients. Overall, understanding the complex interplay between OSA and nocturia is crucial for optimizing patient outcomes.

The bidirectional relationship between obstructive sleep apnea and atrial fibrillation: Pathophysiology, diagnostic challenges, and strategies - A narrative review

Atrial fibrillation (AF), is an irregular heart rhythm disorder that increases the risk of stroke, heart failure, and death. Obstructive sleep apnea is typified by intermittent airway blockages which results in low oxygen levels and disrupted sleep. These two conditions often coexist, with each worsening the other. Understanding this connection is critical to improve diagnosis and treatment. The relationship between atrial fibrillation and obstructive sleep apnea appears bidirectional. Obstructive sleep apnea increases the risk of atrial fibrillation through various mechanisms which are arrhythmogenic. Conversely, patients with atrial fibrillation are more likely to have undiagnosed obstructive sleep apnea, complicating their treatment. Screening modalities for obstructive sleep apnea are often inadequate. Polysomnography remains the most reliable tool but is costly and not practical for routine screening of all patients which limits early diagnosis and management. Continuous positive airway pressure (CPAP) therapy is the primary treatment for obstructive sleep apnea and can reduce atrial fibrillation recurrence by decreasing oxygen deprivation and sympathetic activity. However, adherence to continuous positive airway pressure is often low due to patient discomfort. Alternative therapies, such as mandibular advancement devices and hypoglossal nerve stimulation, offer promising options for patients who cannot tolerate continuous positive airway pressure. The interplay between atrial fibrillation and obstructive sleep apnea requires an integrated approach to diagnosis and treatment. Improving screening tools, enhancing treatment adherence, and evaluating alternative therapies are critical steps to reducing the impact of these conditions and improving patient outcomes.

Differential effects of sleep position and sleep stage on the severity of obstructive sleep apnea

This study compared the effects of sleeping in the supine position and rapid eye movement sleep on the severity of obstructive sleep apnea, and investigated the effect of sleep stage on position-dependent obstructive sleep apnea, and of sleep position on rapid eye movement-dependent obstructive sleep apnea. We analysed epoch-labelled polysomnographic readouts of 3843 patients, and calculated the apnea-hypopnea index for each sleep position and sleep stage. Subgroup analyses were performed to evaluate whether the proportion of position-dependent obstructive sleep apnea patients changed during rapid eye movement and non-rapid eye movement sleep, and whether that of rapid eye movement-dependent obstructive sleep apnea patients changed during supine/lateral sleep. The apnea-hypopnea index was highest in the rapid eye movement-supine position (50.7 ± 22.6 events per hr), followed by non-rapid eye movement-supine, rapid eye movement-lateral and non-rapid eye movement-lateral (39.2 ± 25.3, 22.9 ± 24.4, 15.9 ± 21.9 events per hr, respectively; p < 0.001). Patients with position-dependent obstructive sleep apnea had a higher ratio of rapid eye movement sleep, and those with rapid eye movement-dependent obstructive sleep apnea had a higher ratio of sleep time in the supine position (p < 0.001). During rapid eye movement sleep, position-dependent obstructive sleep apnea was not observed in 21.1% of patients who otherwise had position-dependent obstructive sleep apnea. In the lateral position, 36.9% of patients with rapid eye movement-dependent obstructive sleep apnea did not retain rapid eye movement dependency. Although sleeping in the supine position and rapid eye movement sleep were both associated with more frequent respiratory events, this was the first study to demonstrate that the former had a stronger correlation with obstructive sleep apnea severity. Position dependency in patients with obstructive sleep apnea decreased during rapid eye movement sleep, and worsening of rapid eye movement dependency was alleviated in the lateral position, suggesting potential for personalized obstructive sleep apnea management.

Influence of sleep on physiological systems in atherosclerosis

Sleep is a fundamental requirement of life and is integral to health. Deviation from optimal sleep associates with numerous diseases including those of the cardiovascular system. Studies, spanning animal models to humans, show that insufficient, disrupted or inconsistent sleep contribute to poor cardiovascular health by disrupting body systems. Fundamental experiments have begun to uncover the molecular and cellular links between sleep and heart health while large-scale human studies have associated sleep with cardiovascular outcomes in diverse populations. Here, we review preclinical and clinical findings that demonstrate how sleep influences the autonomic nervous, metabolic and immune systems to affect atherosclerotic cardiovascular disease.

Advances in the use of dexmedetomidine during the perioperative period to improve postoperative sleep quality in patients undergoing surgery

There is a high incidence of postoperative sleep and sleep architecture disorders in patients undergoing surgery, and dexmedetomidine (DEX) is commonly used to improve postoperative sleep quality and ameliorate the adverse effects of poor sleep on various organ systems. The continuous intraoperative intravenous infusion of DEX, the addition of DEX to postoperative intravenous analgesia pumps, and the continuous infusion of DEX after admission to the intensive care unit are often used clinically to improve postoperative sleep quality at doses of 0.1 to 0.7 μg/kg/hour, but the effects of DEX on sleep quality and structure identified in these studies have been inconsistent. Thus, it is unclear whether DEX improves postoperative sleep quality. The various methods of administering DEX to improve postoperative sleep quality have differing effects, the route used modifies the effect of DEX on sleep structure, and the intrinsic mechanism whereby DEX improves sleep quality remains to be fully investigated. In the present review, we describe new directions for future research into the effects of DEX on postoperative sleep quality and the mechanisms involved, which should help guide the design of further studies. This narrative review was completed according to the Scale for the Assessment of Narrative Review Articles (SANRA).

The effect of unhealthy lifestyle on the pathogenesis of sick sinus syndrome: A life-guiding review

Sick sinus syndrome (SSS), also known as sinoatrial node dysfunction, has been widely concerned by the medical community. The incidence rate of SSS is increasingly, which poses a great threat to public health. Through decades of repeated research in the medical field, great progress has been made in the pathogenesis of SSS and the interaction mechanism between SSS and other cardiovascular diseases. In this paper, we pay special attention to the mental stimulation factors under various pressures such as society and work, and the influence of smoking, drinking, and unhealthy diet on the pathogenesis of SSS. It also explains the mechanism of negative factors in the pathogenesis of SSS. These unhealthy lifestyle will lead to the occurrence of sinoatrial node disease and arrhythmia, and then induce SSS. Therefore, in the premise of increasing incidence rate of SSS and difficult to cure, how to avoid these harmful factors and ensure a healthy lifestyle is extremely important for preventing and treating SSS. This study also has guiding significance for the daily life of high-risk population of SSS and reducing the mortality of SSS patients.

Assessment of sleep characteristics using Fitbit Charge 4 in head and neck cancer patients undergoing palliative chemotherapy and radiotherapy: a prospective observational study

Background

Sleep disturbance is prevalent among cancer patients. The quantification of this sleep disturbance is missing, especially in palliative care settings.

Aim

The aim of this study was to study the sleep patterns of the patients undergoing palliative chemotherapy and radiotherapy for head and neck cancer (HNC) using a Fitbit Charge 4 sleep-tracking device.

Design

Prospective observational study.

Setting

A total of 110 HNC patients undergoing palliative chemotherapy and radiotherapy at a tertiary care teaching hospital in Central India.

Results

Forty-four percent of patients had a poor sleep score (less than 60). Average sleep duration was 218.66 ± 139.05 min; non-rapid eye movement (NREM) sleep duration 197.7 ± 115.91 (light NREM 171.36 ± 104 and deep NREM 23.36 ± 16.73); REM sleep duration was 30.44 ± 34.14 min. The Pittsburgh Sleep Quality Index was 10.23 ± 3.45, which indicated sleep deprivation over the past 1 month. Moderate levels of anxiety, depression, confusion, and distress existed in the cohort. Statistically significant but weak correlation existed between sleep score, anxiety, and depression. Strong correlation existed between distress score and sleep score. Confusion score did not have a significant correlation with sleep score.

Conclusion

HNC patients in palliative care settings were chronically sleep deprived. Sleep architecture was also disturbed. Moderate levels of anxiety, depression, confusion, and distress existed in the studied cohort; these psychosocial disturbances had a weak correlation with the sleep score and are likely to be multifactorial.

Trial registration

Institutional Ethics Committee number: IHEC-LOP/2020/IM0349. The study has been registered with clinical trial registry of India with registration number CTRI/2021/03/032400 (http://www.ctri.in).

Cardiac autonomic function in REM-related obstructive sleep apnoea: insights from nocturnal heart rate variability profiles

PURPOSE

In light of the reported association between REM-related obstructive sleep apnoea (OSA) and heightened cardiovascular risk, this study aims to compare cardiac autonomic function in patients with REM-OSA and OSA independent of sleep stage. We hypothesized that REM-OSA patients would exhibit higher sympathetic cardiac modulation based on heart rate variability (HRV) profiles.

METHODS

HRV was compared between the OSA group (AHI ≥ 5 events/h, n = 252) and the REM-OSA group (AHI ≥ 5 events/h, AHIREM:AHINREM ≥ 2, n = 137). Time- and frequency-domain measures of HRV were analysed during N2 and REM sleep.

RESULTS

Clinical characteristics between the two test groups differed significantly, 45% of REM-OSA patients were female, with mild OSA (median, interquartile range (IQR)) AHI of 10 (7) events/h. Only 26% of the OSA cohort were female with moderate OSA (AHI = 17 (20) events/h, p < 0.001). Compared with the OSA group, the low frequency to high frequency ratio (LF:HF) and LF power were lower and HF power was higher in the REM-OSA group during N2 (LF:HF, p = 0.012; LF; p = 0.013; HF, p = 0.007) and in REM sleep (LF:HF, p = 0.002; LF, p = 0.004; HF, p < 0.001). Patient sex and OSA severity had a significant combined effect on average N to N interval, LF power, and LF:HF ratio during N2 and REM sleep (all p < 0.001).

CONCLUSION

Contrary to our hypothesis, REM-OSA patients demonstrated consistently higher cardiac vagal modulation, reflecting better cardiac autonomic adaptation. These results were attributed to differences in OSA severity and sex in these two groups, both independently affecting HRV. This study emphasises the need for future research into the underlying pathophysiology of REM-OSA and the potential implications of sex and OSA severity on cardiovascular risk.

Renal autonomic dynamics in hypertension: how can we evaluate sympathetic activity for renal denervation?

This review explores the various pathophysiological factors influencing antihypertensive effects, involving the regulation of vascular resistance, plasma volume, cardiac function, and the autonomic nervous system, emphasizing the interconnected processes regulating blood pressure (BP). The kidney's pivotal role in BP control and its potential contribution to hypertension is complicated but important to understand the effective mechanisms of renal denervation (RDN), which may be a promising treatment for resistant hypertension. Excessive stimulation of the sympathetic nervous system or the renin-angiotensin-aldosterone system (RAAS) can elevate BP through various physiological changes, contributing to chronic hypertension. Renal sympathetic efferent nerve activation leads to elevated norepinephrine levels and subsequent cascading effects on vasoconstriction, renin release, and sodium reabsorption. RDN reduces BP in resistant hypertension by potentially disrupting sensory afferent nerves, decreasing feedback activation to the central nervous system, and reducing efferent sympathetic nerve activity in the heart and other structures. RDN may also modulate central sympathetic outflow and inhibit renal renin-angiotensin system overactivation. While evidence for RDN efficacy in hypertension is increasing, accurate patient selection becomes crucial, considering complex interactions that vary among patients. This review also discusses methods to evaluate autonomic nerve activity from the golden standard to new potential examination for finding out optimization in stimulation parameters or rigorous patient selection based on appropriate biomarkers.

Circadian rhythm of brain-derived neurotrophic factor in serum and plasma

The neurotrophic growth factor brain-derived neurotrophic factor (BDNF) plays a crucial role in various neurodegenerative and psychiatric diseases, such as Alzheimer's disease, schizophrenia and depression. BDNF has been proposed as a potential biomarker for diagnosis, prognosis and monitoring therapy. Understanding the factors influencing BDNF levels and whether they follow a circadian rhythm is essential for interpreting fluctuations in BDNF measurements. We aimed to investigate the circadian rhythm of BDNF by collecting multiple peripheral venous blood samples from young, healthy male participants at 12 different time points over 24 h. In addition, vital parameters, cortisol and insulin like growth factor 1 (IGF1) were measured to explore potential regulatory mechanisms, interfering variables and their correlations with BDNF concentration. The findings revealed that plasma BDNF did not exhibit any significant fluctuations over 24 h, suggesting the absence of a circadian rhythm. However, serum BDNF levels decreased during sleep. Furthermore, serum BDNF showed a positive correlation with heart rate but a negative correlation with IGF1. No significant correlation was observed between cortisol and BDNF or IGF1. Although plasma BDNF suggests steady-state conditions, the decline of serum BDNF during the nocturnal period could be attributed to physical inactivity and associated with reduced haemodynamic blood flow (heart rate reduction during sleep). The type of sample collection (peripheral venous cannula vs. blood sampling using a butterfly system) does not significantly affect the measured BDNF levels. The sample collection during the day did not significantly affect BDNF analysis, emphasizing the importance of considering activity levels rather than timing when designing standardized protocols for BDNF assessments.

Interactions of Obstructive Sleep Apnea With the Pathophysiology of Cardiovascular Disease, Part 1: JACC State-of-the-Art Review

The American Heart Association considers sleep health an essential component of cardiovascular health, and sleep is generally a time of cardiovascular quiescence, such that any deviation from normal sleep may be associated with adverse cardiovascular consequences. Many studies have shown that both impaired quantity and quality of sleep, particularly with obstructive sleep apnea (OSA) and comorbid sleep disorders, are associated with incident cardiometabolic consequences. OSA is associated with repetitive episodes of altered blood gases, arousals, large negative swings in intrathoracic pressures, and increased sympathetic activity. Recent studies show that OSA is also associated with altered gut microbiota, which could contribute to increased risk of cardiovascular disease. OSA has been associated with hypertension, atrial fibrillation, heart failure, coronary artery disease, stroke, and excess cardiovascular mortality. Association of OSA with chronic obstructive lung disease (overlap syndrome) and morbid obesity (obesity hypoventilation syndrome) increases the odds of mortality.

Sleep Apnea, Autonomic Disturbances, and Blood Pressure Variability

Augmented blood pressure variability has emerged as a quantity predictive of adverse cardiovascular outcomes. Among the range of intrinsic and extrinsic factors shown to increase night-time, circadian, short-term, and long-term blood pressure variations, the presence and severity of obstructive sleep apnea have emerged as one of the most prevalent and potent. Obstructive sleep apnea alters acutely the normal nocturnal equilibrium between sympathetic and parasympathetic tone, magnifying nocturnal blood pressure oscillations, and induces sustained autonomic aftereffects with the capacity to amplify short-term and intersessional blood pressure variabilities. The object of this brief review is to synthesize the current understanding of the potential interrelations between obstructive sleep apnea, the acute and sustained autonomic disturbances that it elicits, and beat-to-beat blood pressure fluctuation during sleep, nocturnal dipping status, and day-to-day blood pressure variability and the consequences of these perturbations for cardiovascular risk.

Sleep patterns and risk of chronic disease as measured by long-term monitoring with commercial wearable devices in the All of Us Research Program

Poor sleep health is associated with increased all-cause mortality and incidence of many chronic conditions. Previous studies have relied on cross-sectional and self-reported survey data or polysomnograms, which have limitations with respect to data granularity, sample size and longitudinal information. Here, using objectively measured, longitudinal sleep data from commercial wearable devices linked to electronic health record data from the All of Us Research Program, we show that sleep patterns, including sleep stages, duration and regularity, are associated with chronic disease incidence. Of the 6,785 participants included in this study, 71% were female, 84% self-identified as white and 71% had a college degree; the median age was 50.2 years (interquartile range = 35.7, 61.5) and the median sleep monitoring period was 4.5 years (2.5, 6.5). We found that rapid eye movement sleep and deep sleep were inversely associated with the odds of incident atrial fibrillation and that increased sleep irregularity was associated with increased odds of incident obesity, hyperlipidemia, hypertension, major depressive disorder and generalized anxiety disorder. Moreover, J-shaped associations were observed between average daily sleep duration and hypertension, major depressive disorder and generalized anxiety disorder. These findings show that sleep stages, duration and regularity are all important factors associated with chronic disease development and may inform evidence-based recommendations on healthy sleeping habits.

Assessment of the gut microbiota of children with obstructive sleep apnea syndrome: A systematic review

Sleep-disordered breathing promotes not only unfavorable craniofacial changes in untreated pediatric patients but also neurocognitive, metabolic, cardiovascular, and even long-term social alterations. This systematic review evaluated whether children diagnosed with obstructive sleep apnea syndrome (OSAS) have different intestinal microbiota constitutions from healthy children and was based on the PRISMA guidelines (PROSPERO: CRD42022360074). A total of 1562 clinical studies published between 2019 and 2023 were selected from the PubMed/MEDLINE, Embase, Web of Science, Scopus, and Cochrane Library databases, of which five were included in the qualitative analysis, three being randomized and two prospective. The methodological quality was assessed (RoB 2.0 and ROBINS-I) and all studies showed a negative effect of intervention. Sleep deprivation and intermittent hypoxia in children with OSAS seem to trigger a cascade of inflammatory pathways that exacerbate the tissue response to the release of reactive oxygen species and the generation of oxidative stress, leading to a reduction in oxygen supply to the intestinal mucosa and the integral destruction of the intestinal barrier. More evidence-based investigations are needed to optimize the identification of possible alterations in the gut microbiota of pediatric patients, given that its composition may be influenced by the patient's sleep quality and, consequently, by OSAS, showing quantitative and qualitative alterations compared to that found in healthy individuals.

Characteristics of obstructive sleep apnea related to insulin resistance

BACKGROUND

Obstructive sleep apnea (OSA) is associated with multiple comorbidities, including diabetes. Its development is preceded by alterations in the initial phase of carbohydrate metabolism characterized by insulin resistance. This study aims to evaluate the role of intermittent hypoxia and sleep fragmentation characteristic of OSA on the risk of insulin resistance among apneic patients without diabetes.

METHODOLOGY

92 consecutive patients with OSA without evidence of diabetes were recruited. Overnight video polysomnography was performed and, the following morning, fasting blood glucose, insulin and glycosylated hemoglobin were determined. Insulin resistance was measured using the HOMA-IR index.

RESULTS

Insulin resistance was present in 52.2% of OSA patients. In these subjects, insulin resistance was independently associated to the apnea index during REM sleep (adjusted odds ratio [aOR] 1.09; 95% CI, 1.03 to 1.16; p = 0.004), desaturation index (aOR 1.08; 95% CI: 1.04 to 1.13; p = 0.027), and sleep time with oxygen saturation below 90% (aOR 1.04; 95% CI 1.00 to 1.08; p = 0.049). Furthermore, the HOMA-IR level was also directly related to the desaturation index (standardized regression coefficient [B] = 0.514, p < 0.001) and to the apnea index during REM sleep (B = 0.344, p = 0.002).

CONCLUSIONS

Intermittent hypoxia and disturbances in REM sleep emerge as main contributors to insulin resistance in OSA patients yet to experience diabetes onset.

Eating Around the Clock: Circadian Rhythms of Eating and Metabolism

The time of day that we eat is increasingly recognized as contributing as importantly to overall health as the amount or quality of the food we eat. The endogenous circadian clock has evolved to promote intake at optimal times when an organism is intended to be awake and active, but electric lights and abundant food allow eating around the clock with deleterious health outcomes. In this review, we highlight literature pertaining to the effects of food timing on health, beginning with animal models and then translation into human experiments. We emphasize the pitfalls and opportunities that technological advances bring in bettering understanding of eating behaviors and their association with health and disease. There is great promise for restricting the timing of food intake both in clinical interventions and in public health campaigns for improving health via nonpharmacological therapies.

Inverse association between slow-wave sleep and low-grade inflammation in children and adolescents with major depressive disorder

OBJECTIVE

To investigate the relationship between both self-reported and objective sleep variables and low-grade inflammation in children and adolescents with major depressive disorder (MDD) of moderate to severe symptom severity.

METHODS

In this cross-sectional study, we examined twenty-nine children and adolescents diagnosed with MDD and twenty-nine healthy controls (HC). Following a one-week actigraphy assessment, comprehensive sleep evaluations were conducted, including a one-night sleep EEG measurement and self-reported sleep data. Plasma high-sensitivity C-reactive protein (hsCRP) was employed as a marker to assess low-grade inflammation.

RESULTS

No significant difference in hsCRP levels was observed between participants with MDD and HC. Furthermore, after adjusting for sleep difficulties, hsCRP exhibited no correlation with the severity of depressive symptoms. In HC, levels of hsCRP were not linked to self-reported and objective sleep variables. In contrast, depressed participants showed a significant correlation between hsCRP levels and increased subjective insomnia severity (Insomnia Severity Index; r = 0.41, p < 0.05), increased time spent in the N2 sleep stage (r = 0.47, p < 0.01), and decreased time spent in slow-wave sleep (r = - 0.61, p < 0.001). Upon additional adjustments for body mass index, tobacco use and depression severity, only the inverse association between hsCRP and time spent in slow-wave sleep retained statistical significance. Moderation analysis indicated that group status (MDD vs. HC) significantly moderates the association between slow-wave sleep and hsCRP.

CONCLUSION

Our findings suggest that alterations in the architecture of slow-wave sleep may have a significant influence on modulating low-grade inflammatory processes in children and adolescents with MDD.

Association Between Sleep Duration and Atrial Fibrillation: A Narrative Review

Sleep duration is a substantial risk factor for several cardiovascular diseases, including atrial fibrillation (AF). Despite much research, the precise nature of the relationship between the amount of sleep and AF remains unclear. This narrative review explores the relationship between AF and sleep duration, looking at genetic, mechanistic, and epidemiological data to explain this association. A U-shaped association (nonlinear relationship or curvilinear association) between sleep duration and AF has been seen, where longer and shorter sleep duration, more or less than seven to eight hours, have been associated with increased AF risk. Multiple mechanisms such as autonomic dysfunction, inflammation, and structural atrial remodeling have been proposed linking sleep disturbances to AF. Moreover, confounding factors such as individual lifestyle, comorbidities, and sleep quality could affect this association. Additionally, the interpretation of study results is further impacted by methodological limitations, including self-reported sleep duration and observational study designs. It is imperative to comprehend the complex relationship between sleep duration and AF to develop effective preventive and therapeutic methods. The main goals of future research should focus on prospective cohort studies with objective sleep metrics, exploring the mechanistic pathways, and comprehensive confounder adjustments that link sleep disturbances to AF. In summary, addressing sleep disturbances may represent one of the novel approaches to AF prevention and management, with potential implications for improving cardiovascular health and reducing AF-related morbidity and mortality.

Associations of Subjective Sleep Quality with Wearable Device-Derived Resting Heart Rate During REM Sleep and Non-REM Sleep in a Cohort of Japanese Office Workers

Background

Associations between subjective sleep quality and stage-specific heart rate (HR) may have important clinical relevance when aiming to optimize sleep and overall health. The majority of previously studies have been performed during short periods under laboratory-based conditions. The aim of this study was to investigate the associations of subjective sleep quality with heart rate during REM sleep (HR REMS) and non-REM sleep (HR NREMS) using a wearable device (Fitbit Versa).

Methods

This is a secondary analysis of data from the intervention group of a randomized controlled trial (RCT) performed between December 3, 2018, and March 2, 2019, in Tokyo, Japan. The intervention group consisted of 179 Japanese office workers with metabolic syndrome (MetS), Pre-MetS or a high risk of developing MetS. HR was collected with a wearable device and sleep quality was assessed with a mobile application where participants answered The St. Mary's Hospital Sleep Questionnaire. Both HR and sleep quality was collected daily for a period of 90 days. Associations of between-individual and within-individual sleep quality with HR REMS and HR NREMS were analyzed with multi-level model regression in 3 multivariate models.

Results

The cohort consisted of 92.6% men (n=151) with a mean age (± standard deviation) of 44.1 (±7.5) years. A non-significant inverse between-individual association was observed for sleep quality with HR REMS (HR REMS -0.18; 95% CI -0.61, 0.24) and HR NREMS (HR NREMS -0.23; 95% CI -0.66, 0.21), in the final multivariable adjusted models; a statistically significant inverse within-individual association was observed for sleep quality with HR REMS (HR REMS -0.21 95% CI -0.27, -0.15) and HR NREMS (HR NREMS -0.21 95% CI -0.27, -0.14) after final adjustments for covariates.

Conclusion

The present study shows a statistically significant within-individual association of subjective sleep quality with HR REMS and HR NREMS. These findings emphasize the importance of considering sleep quality on the individual level. The results may contribute to early detection and prevention of diseases associated with sleep quality which may have important implications on public health given the high prevalence of sleep disturbances in the population.

Facilitating ambulatory heart rate variability analysis using accelerometry-based classifications of body position and self-reported sleep

Objective.This study aimed to examine differences in heart rate variability (HRV) across accelerometer-derived position, self-reported sleep, and different summary measures (sleep, 24 h HRV) in free-living settings using open-source methodology.Approach.HRV is a biomarker of autonomic activity. As it is strongly affected by factors such as physical behaviour, stress, and sleep, ambulatory HRV analysis is challenging. Beat-to-beat heart rate (HR) and accelerometry data were collected using single-lead electrocardiography and trunk- and thigh-worn accelerometers among 160 adults participating in the SCREENS trial. HR files were processed and analysed in the RHRV R package. Start time and duration spent in physical behaviours were extracted, and time and frequency analysis for each episode was performed. Differences in HRV estimates across activities were compared using linear mixed models adjusted for age and sex with subject ID as random effect. Next, repeated-measures Bland-Altman analysis was used to compare 24 h RMSSD estimates to HRV during self-reported sleep. Sensitivity analyses evaluated the accuracy of the methodology, and the approach of employing accelerometer-determined episodes to examine activity-independent HRV was described.Main results.HRV was estimated for 31 289 episodes in 160 individuals (53.1% female) at a mean age of 41.4 years. Significant differences in HR and most markers of HRV were found across positions [Mean differences RMSSD: Sitting (Reference) - Standing (-2.63 ms) or Lying (4.53 ms)]. Moreover, ambulatory HRV differed significantly across sleep status, and poor agreement between 24 h estimates compared to sleep HRV was detected. Sensitivity analyses confirmed that removing the first and last 30 s of accelerometry-determined HR episodes was an accurate strategy to account for orthostatic effects.Significance.Ambulatory HRV differed significantly across accelerometry-assigned positions and sleep. The proposed approach for free-living HRV analysis may be an effective strategy to remove confounding by physical activity when the aim is to monitor general autonomic stress.

High-Frequency Heart Rate Variability Is Prospectively Associated With Sleep Complaints in a Healthy Working Cohort

OBJECTIVE

Vagus nerve functioning, as indexed by high-frequency heart rate variability (HF-HRV), has been implicated in a wide range of mental and physical health conditions, including sleep complaints. This study aimed to test associations between HF-HRV measured during sleep (sleep HF-HRV) and subjective sleep complaints 4 years later.

METHODS

One hundred forty-three healthy employees (91% male; MAge = 47.8 years [time 2], SD = 8.3 years) of an industrial company in Southern Germany completed the Jenkins Sleep Problems Scale, participated in a voluntary health assessment, and were given a 24-hour ambulatory heart rate recording device in 2007. Employees returned for a health assessment and completed the Jenkins Sleep Problems Scale 4 years later.

RESULTS

Hierarchical regression analyses showed that lower sleep HF-HRV measured in 2007 was associated with higher self-reported sleep complaints 4 years later after controlling for covariates (rab,c = -0.096, b = -0.108, 95% CI, -0.298 to 0.081, ΔR2 = 0.009, p = .050).

CONCLUSIONS

These data are the first to show that lower sleep HF-HRV predicted worse sleep 4 years later, highlighting the importance of vagus nerve functioning in adaptability and health.

Beat-to-beat cardiac repolarization lability increases during hypoxemia and arousals in obstructive sleep apnea patients

Obstructive sleep apnea (OSA) is associated with the progression of cardiovascular diseases, arrhythmias, and sudden cardiac death (SCD). However, the acute impacts of OSA and its consequences on heart function are not yet fully elucidated. We hypothesized that desaturation events acutely destabilize ventricular repolarization, and the presence of accompanying arousals magnifies this destabilization. Ventricular repolarization lability measures, comprising heart rate corrected QT (QTc), short-time-variability of QT (STVQT), and QT variability index (QTVI), were calculated before, during, and after 20,955 desaturations from lead II electrocardiography signals of 492 patients with suspected OSA (52% men). Variations in repolarization parameters were assessed during and after desaturations, both with and without accompanying arousals, and groupwise comparisons were performed based on desaturation duration and depth. Regression analyses were used to investigate the influence of confounding factors, comorbidities, and medications. The standard deviation (SD) of QT, mean QTc, SDQTc, and STVQT increased significantly (P < 0.01), whereas QTVI decreased (P < 0.01) during and after desaturations. The changes in SDQT, mean QTc, SDQTc, and QTVI were significantly amplified (P < 0.01) in the presence of accompanying arousals. Desaturation depth was an independent predictor of increased SDQTc (β = 0.405, P < 0.01), STVQT (β = 0.151, P < 0.01), and QTVI (β = 0.009, P < 0.01) during desaturation. Desaturations cause acute changes in ventricular repolarization, with deeper desaturations and accompanying arousals independently contributing to increased ventricular repolarization lability. This may partially explain the increased risk of arrhythmias and SCD in patients with OSA, especially when the OSA phenotype includes high hypoxic load and fragmented sleep.NEW & NOTEWORTHY Nocturnal desaturations are associated with increased ventricular repolarization lability. Deeper desaturations with accompanying arousals increase the magnitude of alterations, independent of confounding factors, comorbidities, and medications. Changes associated with desaturations can partially explain the increased risk of arrhythmias and sudden cardiac death in patients with OSA, especially in patients with high hypoxic load and fragmented sleep. This highlights the importance of detailed electrocardiogram analytics for patients with OSA.

Sleep stage prediction using multimodal body network and circadian rhythm

Quality sleep plays a vital role in living beings as it contributes extensively to the healing process and the removal of waste products from the body. Poor sleep may lead to depression, memory deficits, heart, and metabolic problems, etc. Sleep usually works in cycles and repeats itself by transitioning into different stages of sleep. This study is unique in that it uses wearable devices to collect multiple parameters from subjects and uses this information to predict sleep stages and sleep patterns. For the multivariate multiclass sleep stage prediction problem, we have experimented with both memoryless (ML) and memory-based models on seven database instances, that is, five from the collected dataset and two from the existing datasets. The Random Forest classifier outclassed the ML models that are LR, MLP, kNN, and SVM with accuracy (ACC) of 0.96 and Cohen Kappa 0.96, and the memory-based model long short-term memory (LSTM) performed well on all the datasets with the maximum attained accuracy of 0.88 and Kappa 0.82. The proposed methodology was also validated on a longitudinal dataset, the Multiethnic Study of Atherosclerosis (MESA), with ACC and Kappa of 0.75 and 0.64 for ML models and 0.86 and 0.78 for memory-based models, respectively, and from another benchmarked Apple Watch dataset available on Physio-Net with ACC and Kappa of 0.93 and 0.93 for ML and 0.92 and 0.87 for memory-based models, respectively. The given methodology showed better results than the original work and indicates that the memory-based method works better to capture the sleep pattern.

Anatomical Substrates of Rapid Eye Movement Sleep Rebound in a Rodent Model of Post-sevoflurane Sleep Disruption

BACKGROUND

Previous research suggests that sevoflurane anesthesia may prevent the brain from accessing rapid eye movement (REM) sleep. If true, then patterns of neural activity observed in REM-on and REM-off neuronal populations during recovery from sevoflurane should resemble those seen after REM sleep deprivation. In this study, the authors hypothesized that, relative to controls, animals exposed to sevoflurane present with a distinct expression pattern of c-Fos, a marker of neuronal activation, in a cluster of nuclei classically associated with REM sleep, and that such expression in sevoflurane-exposed and REM sleep-deprived animals is largely similar.

METHODS

Adult rats and Targeted Recombination in Active Populations mice were implanted with electroencephalographic electrodes for sleep-wake recording and randomized to sevoflurane, REM deprivation, or control conditions. Conventional c-Fos immunohistochemistry and genetically tagged c-Fos labeling were used to quantify activated neurons in a group of REM-associated nuclei in the midbrain and basal forebrain.

RESULTS

REM sleep duration increased during recovery from sevoflurane anesthesia relative to controls (157.0 ± 24.8 min vs. 124.2 ± 27.8 min; P = 0.003) and temporally correlated with increased c-Fos expression in the sublaterodorsal nucleus, a region active during REM sleep (176.0 ± 36.6 cells vs. 58.8 ± 8.7; P = 0.014), and decreased c-Fos expression in the ventrolateral periaqueductal gray, a region that is inactive during REM sleep (34.8 ± 5.3 cells vs. 136.2 ± 19.6; P = 0.001). Fos changes similar to those seen in sevoflurane-exposed mice were observed in REM-deprived animals relative to controls (sublaterodorsal nucleus: 85.0 ± 15.5 cells vs. 23.0 ± 1.2, P = 0.004; ventrolateral periaqueductal gray: 652.8 ± 71.7 cells vs. 889.3 ± 66.8, P = 0.042).

CONCLUSIONS

In rodents recovering from sevoflurane, REM-on and REM-off neuronal activity maps closely resemble those of REM sleep-deprived animals. These findings provide new evidence in support of the idea that sevoflurane does not substitute for endogenous REM sleep.

EDITOR’S PERSPECTIVE

Association between sleep pattern and incidence of hypertension: A prospective cohort study of older adult participants in the Chinese longitudinal healthy longevity survey

BACKGROUND

The relationship between sleep duration or sleep quality and the risk of hypertension has been previously examined. However, little is known regarding the association between sleep duration and quality and the risk of developing hypertension in the older adult Chinese population.

METHODS

The sleep patterns of 5683 participants without hypertension at baseline from the Chinese Longitudinal Healthy Longevity Survey were analyzed. Cox proportional hazard models were used to study the associations between sleep patterns and hypertension.

RESULTS

It was found that 1712 (30.12%) of the 5683 participants had an unhealthy sleep pattern. After an average follow-up of 3.31 years, 1350 of the participants had hypertension. Compared with participants with an unhealthy sleep pattern, those with a healthy sleep pattern had a 20% (hazard ratio = 0.80, 95% confidence interval = 0.67-0.94, P = = 0.008) lower risk of incident hypertension in the fully adjusted models. In addition, an approximately linear dose-response association was observed between sleep duration and the incidence of hypertension (P for non-linear =0.43). Subgroup analyses demonstrated significant interactions between age and sleep pattern concerning hypertension (P for interaction <0.05). Several sensitivity analyses were conducted, and the obtained findings were similar to the main results.

CONCLUSIONS

A healthy sleep pattern, comprising an adequate sleep duration and good sleep quality, can help reduce hypertension risk. Thus, a healthy sleep pattern is crucial to decreasing hypertension in older Chinese adults in a rapidly aging society.