Insomnia and cardiovascular autonomic control

The Association Between 24-Hour Blood Pressure Profiles and Dementia

Midlife hypertension increases risk for dementia. Around one third of adults have diagnosed hypertension; however, many adults are undiagnosed, or remain hypertensive despite diagnosis or treatment. Since blood pressure (BP) follows a circadian rhythm, ambulatory BP monitoring allows for the assessment of BP over a 24-hour period and provides an important tool for improving the diagnosis and management of hypertension. The measurement of 24-hour BP profiles, especially nocturnal BP, demonstrate better predictive ability for cardiovascular disease and mortality than office measurement. However, few studies have examined 24-hour BP profiles with respect to dementia risk. This is an important topic since improvements in BP management could facilitate the primary prevention of vascular cognitive impairment and dementia. Therefore, this review discusses the evidence linking BP to dementia, with a focus on whether the implementation of 24-hour BP measurements can improve risk prediction and prevention strategies. Pathways linking nocturnal BP to dementia are also discussed as are risk reduction strategies. Overall, limited research suggests an association between 24-hour BP elevation and poorer cognition, cerebral small vessel disease, and dementia. However, most studies were cross-sectional. Further evidence is needed to substantiate 24-hour BP profiles, over and above office BP, as predictors of vascular cognitive impairment and incident dementia.

Orexin, Sleep, Sympathetic Neural Activity, and Cardiovascular Function

Inadequate sleep duration and quality are associated with reduced cardiovascular health and increased mortality. Experimental evidence points to the sympathetic nervous system as a key mediator in the observed relationship between poor sleep and cardiovascular dysfunction. However, brain mechanisms underpinning the impaired sympathetic function associated with poor sleep remain unclear. Recent evidence suggests the central orexin system, particularly orexins A and B and their receptors, have a key regulatory role for sleep in animal and human models. While orexin system activity has been observed to significantly impact sympathetic regulation in animals, the extension of these findings to humans has been difficult due to an inability to directly assess orexin system activity in humans. However, direct measures of sympathetic activity in populations with narcolepsy and chronic insomnia, 2 sleep disorders associated with deficient and excessive orexin neural activity, have allowed indirect assessment of the relationships between orexin, sleep, and sympathetic regulation. Further, the recent pharmaceutical development of dual orexin receptor antagonists for use in clinical insomnia populations offers an unprecedented opportunity to examine the mechanistic role of orexin in sleep and cardiovascular health in humans. The current review assesses the role of orexin in both sleep and sympathetic regulation from a translational perspective, spanning animal and human studies. The review concludes with future research directions necessary to fully elucidate the mechanistic role for orexin in sleep and sympathetic regulation in humans.

Effect of Cognitive-Behavioral Therapy on Nocturnal Autonomic Activity in Patients with Fibromyalgia: A Preliminary Study

Objective: fibromyalgia is a complex chronic pain syndrome characterized by widespread musculoskeletal pain, insomnia and autonomic alterations. Cognitive-behavioral therapy (CBT) is regarded as a promising treatment in fibromyalgia, but its impact on autonomic function remains uncertain. In this research, we studied the effect of CBT on autonomic functions in fibromyalgia. Methods: Twenty-five participants underwent overnight polysomnographic recordings before and after CBT programs focused on pain (CBT-P) or a hybrid modality focused on pain and insomnia (CBT-C). Sleep quality, daily pain, depression and anxiety were assessed by self-reported questionnaires. We analyzed heart rate variability (HRV) using high-frequency power (HF) as a marker for parasympathetic activity, and low-frequency power (LF) and the LF/HF ratio as relative sympathetic markers during wakefulness and at each sleep stage. Results: After treatment, 14 patients (/25, 58.0%) reported improvement in their sleep: 6 in the CBT-P condition (/12, 50%), and 8 in the CBT-C condition (/13, 61.5%). We found that, regardless of the type of CBT, patients who reported improvement in sleep quality (n = 14, 58%) had an increase in HF during stages N2 (p < 0.05) and N3 (p < 0.05). These changes were related to improvement in sleep quality (N2, r = −0.43, p = 0.033) but not to pain, depression or anxiety. Conclusions: This study showed an improvement in parasympathetic cardiac control during non-rapid-eye-movement sleep following CBT in fibromyalgia participants who reported better sleep after this therapy. CBT may have a cardio-protective effect and HRV could be used as a sleep monitoring tool in fibromyalgia.

A virtual reality-based mind–body approach to downregulate psychophysiological arousal in adolescent insomnia

Objective

In this study, we describe the rationale, supported by preliminary data, for a novel, digital, immersive virtual reality (VR)-based mind–body approach, designed to reduce bedtime arousal in adolescents with insomnia.

Methods

Fifty-two high-school students (16–20 years; 32 female) with ( N = 18) and without ( N = 34) DSM-5 insomnia symptoms engaged with 20 min of immersive VR-guided meditation and paced breathing (0.1 Hz) ( intervention condition) and 20 min of quiet activity ( control condition), right before bedtime, on two separate evenings.

Results

The intervention resulted in acute autonomic and cortical modulation ( p < 0.05), leading to reduced physiological arousal (↓heart rate, ↓cortisol) compared with the control condition, with similar effects in adolescents with and without insomnia. No significant changes were detected for cognitive arousal levels. During the intervention, all participants were able to achieve the targeted 0.1 Hz breathing rate, and the majority experienced no discomfort associated with the VR exposure. However, 30–40% of the participants experienced some trouble slowing down their breathing.

Conclusions

The study provides supporting preliminary evidence for the mechanism behind a novel VR-based digital approach, designed to regulate psychophysiological arousal levels by acting on neurocognitive and autonomic pathways. Further studies (e.g. randomized clinical trials) are needed to evaluate the isolated and synergistic effects of its components (e.g. VR vs. VR + paced breathing), and its efficacy, acceptance, and feasibility in alleviating insomnia symptoms in adolescents.

[Objective sleep characteristics and risk factors for sleep apnea in heart failure patients with different left ventricular ejection fraction]

OBJECTIVE

To investigate the objective sleep characteristics and the independent risk factors for sleep apnea in heart failure (HF) patients with different left ventricular ejection fractions (LVEF).

METHODS

A total of 107 patients with chronic HF hospitalized in the Department of Cardiology of our hospital from April, 2019 to October, 2020 were included in this study. According to the LVEF measured by echocardiography, the patients were divided into reduced ejection fraction (HFrEF) group (n=35), mid-range ejection fraction (HFmrEF) group (n=21), and preserved ejection fraction (HFpEF) group (n=51). The baseline demographic and clinical characteristics of the patients were recorded. To assess the objective sleep characteristics, whole night polysomnography was scheduled for all the patients. Spearman correlation and multinomial logistic regression analyses were used to explore the factors affecting objective sleep characteristics.

RESULTS

The patients in HFpEF group had significantly lower proportion of non-rapid eye movement sleep stage 1, apnea hypopnea index (AHI), and central sleep apnea (CSA) than those in HFrEF group (all P < 0.05). The baseline demographic data or sleep structures in HFmrEF group did not differ significantly from those in the other two groups. Spearman correlation analysis revealed significant correlations of the male sex, diuretics use, NT-proBNP, LVEF, and total cholesterol levels with the severity of AHI (all P < 0.05). After adjusting for potential confounders, multiple logistics regression analysis showed that age, drinking, and LVEF levels were independently associated with the severity of AHI (all P < 0.05).

CONCLUSION

Abnormal objective sleep architectures occur in all HF patients, manifested mainly by sleep apnea. The incidences of sleep apnea and CSA are lower in patients with HFpEF than in those with HFrEF. Age, drinking, and LVEF levels are independent risk factors for the occurrence and severity of sleep apnea.

Chronotherapy

The objective of chronotherapy is to optimize medical treatments taking into account the body's circadian rhythms. Chronotherapy is referred to and practiced in two different ways: (1) to alter the sleep-wake rhythms of patients to improve the sequels of several pathologies; (2) to take into account the circadian rhythms of patients to improve therapeutics. Even minor dysfunction of the biological clock can greatly affect sleep/wake physiology causing excessive diurnal somnolence, increase in sleep onset latency, phase delays or advances in sleep onset, frequent night awakenings, reduced sleep efficiency, delayed and shortened rapid eye movement sleep, or increased periodic leg movements. Chronotherapy aims to restore the proper circadian pattern of the sleep-wake cycle, through adequate sleep hygiene, timed light exposure, and the use of chronobiotic medications, such as melatonin, that affect the output phase of circadian rhythms, thus controlling the clock. Concerning the second use of chronotherapy, therapeutic outcomes as diverse as the survival after open-heart surgery or the efficacy and tolerance to chemotherapy vary according to the time of day. However, humans are heterogeneous concerning the timing of their internal clocks. Not only different chronotypes exist but also the endogenous human circadian period (τ) is not a stable trait as it depends on many internal and external factors. If any scheduled therapeutic intervention is going to be optimized, a tool is needed for simple diagnostic and objectively measurement of an individual's internal time at any given time. Methodologic advances like the use of single-sample gene expression and metabolomics are discussed.

Cardiovascular Complications of Sleep Disorders: A Better Night's Sleep for a Healthier Heart / From Bench to Bedside

Sleep is essential to and an integral part of life and when lacking or disrupted, a multitude of mental and physical pathologies ensue, including cardiovascular (CV) disease, which increases health care costs. Several prospective studies and meta-analyses show that insomnia, short (<7h) or long (>9h) sleep and other sleep disorders are associated with an increased risk of hypertension, metabolic syndrome, myocardial infarction, heart failure, arrhythmias, CV disease risk and/or mortality. The mechanisms by which insomnia and other sleep disorders lead to increased CV risk may encompass inflammatory, immunological, neuro-autonomic, endocrinological, genetic and microbiome perturbations. Guidelines are emerging that recommend a target of >7 h of sleep for all adults >18 years for optimal CV health. Treatment of sleep disorders includes cognitive-behavioral therapy considered the mainstay of non-pharmacologic management of chronic insomnia, and drug treatment with benzodiazepine receptor agonists binding to gamma aminobutyric acid type A (benzodiazepine and non-benzodiazepine agents) and some antidepressants. However, observational studies and meta-analyses indicate an increased mortality risk of anxiolytics and hypnotics, although bias may be involved due to confounding and high heterogeneity in these studies. Nevertheless, it seems that the risk incurred by the non-benzodiazepine hypnotic agents (Z drugs) may be relatively less than the risk of anxiolytics, with evidence indicating that at least one of these agents, zolpidem, may even confer a lower risk of mortality in adjusted models. All these issues are herein reviewed.