Relation between heart beat fluctuations and cyclic alternating pattern during sleep in insomnia patients

Sleep-Disordered Breathing Risk with Comorbid Insomnia Is Associated with Mild Cognitive Impairment

Introduction: Few studies have evaluated the combined association between SDB with comorbid insomnia and mild cognitive impairment (MCI). To test the hypothesis that SDB with comorbid insomnia is associated with greater odds of MCI than either sleep disorder independently, we used ADNI data to evaluate cross-sectional associations between SDB risk with comorbid insomnia status and MCI. Methods: Participants with normal cognition or MCI were included. Insomnia was defined by self-report. SDB risk was assessed by modified STOP-BANG. Logistic regression models evaluated associations between four sleep disorder subgroups (low risk for SDB alone, low risk for SDB with insomnia, high risk for SDB alone, and high risk for SDB with insomnia) and MCI. Models adjusted for age, sex, BMI, APOE4 genotype, race, ethnicity, education, marital status, hypertension, cardiovascular disease, stroke, alcohol abuse, and smoking. Results: The sample (n = 1391) had a mean age of 73.5 ± 7.0 years, 44.9% were female, 72.0% were at low risk for SDB alone, 13.8% at low risk for SDB with insomnia, 10.1% at high risk for SDB alone, and 4.1% at high risk for SDB with insomnia. Only high risk for SDB with comorbid insomnia was associated with higher odds of MCI (OR 3.22, 95% CI 1.57–6.60). Conclusion: Studies are needed to evaluate SDB with comorbid insomnia as a modifiable risk factor for MCI.

Causality of cortical and cardiovascular activity during cyclic alternating pattern in non-rapid eye movement sleep

The dynamic interplay between central and autonomic nervous system activities plays a pivotal role in orchestrating sleep. Macrostructural changes such as sleep-stage transitions or phasic, brief cortical events elicit fluctuations in neural outflow to the cardiovascular system, but the causal relationships between cortical and cardiovascular activities underpinning the microstructure of sleep are largely unknown. Here, we investigate cortical-cardiovascular interactions during the cyclic alternating pattern (CAP) of non-rapid eye movement sleep in a diverse set of overnight polysomnograms. We determine the Granger causality in both 507 CAP and 507 matched non-CAP sequences to assess the causal relationships between electroencephalography (EEG) frequency bands and respiratory and cardiovascular variables (heart period, respiratory period, pulse arrival time and pulse wave amplitude) during CAP. We observe a significantly stronger influence of delta activity on vascular variables during CAP sequences where slow, low-amplitude EEG activation phases (A1) dominate than during non-CAP sequences. We also show that rapid, high-amplitude EEG activation phases (A3) provoke a more pronounced change in autonomic activity than A1 and A2 phases. Our analysis provides the first evidence on the causal interplay between cortical and cardiovascular activities during CAP. Granger causality analysis may also be useful for probing the level of decoupling in sleep disorders. This article is part of the theme issue 'Advanced computation in cardiovascular physiology: new challenges and opportunities'.

Comorbid Insomnia and Sleep Apnea: mechanisms and implications of an underrecognized and misinterpreted sleep disorder

Sleep-disordered breathing (SDB) and insomnia have long been recognized as important sleep disrupters often associated with increased morbidity and mortality. Although they are often seen as divergent conditions, mainly because their cardinal symptoms (excessive daytime sleepiness, and sleep loss) differ, these two sleep disorders present with many common symptoms, which may hinder diagnosis and treatment. In addition to possible bidirectional pathways between SDB and insomnia, other factors such as circadian timing may play a role. In this paper, we review the mechanisms, differential clinical aspects, and implications of Comorbid Insomnia and Sleep Apnea, sometimes termed COMISA.

Examining the association between Apolipoprotein E (APOE) and self-reported sleep disturbances in non-demented older adults

We aimed to examine the association between Apolipoprotein E (APOE) and sleep disturbances. This is a cross-sectional study, from the Washington Heights-Inwood Community Aging Project (WHICAP). A total of 1944 non-demented older adults took part in the study. Sleep dysfunction was measured using sleep categories derived from the Medical Outcomes Study Sleep Scale. Genetic association between APOE-ϵ4 genotype and sleep disturbances was assessed using unadjusted linear regression models. Secondary analyses were conducted adjusting for age, sex, education, ethnicity and body mass index (BMI). In the unadjusted model, individuals carrying the APOE-ϵ4 allele showed lower levels of snoring (β=-0.02, SE=0.01, p=0.010) and sleep apnea (β=-0.01, SE=0.01, p=0.037) when compared to non-ϵ4 carriers. After covariates' adjustment, ϵ4 carriers demonstrated stronger association with lower levels of both snoring (β=-0.02, SE=0.01, p=0.006), and sleep apnea (β=-0.01, SE=0.01, p=0.018). Our results suggest that APOE-ϵ4 is associated with decreased problems in snoring and sleep apnea, in non-demented older adults.