Insomnia symptoms and subclinical myocardial injury: Data from the Nord-Trøndelag Health (HUNT) study

Understanding the mechanistic interlink between circadian misalignment and heart disease in night shift workers: Therapeutic role of behavioral interventions

BACKGROUND

Rotating and night shift work, especially in older workers, is a growing health concern of modern societies due to the associated high morbidity and mortality rates from cardiovascular disease (CVD). The resulting circadian misalignment disrupts neuroendocrine pathways that regulate cardiovascular physiology, risking myocardial tissue damage and heart dysfunction.

AIMS

Considering the gaps in the literature as to how atypical work behaviors may disrupt the temporal link between the central and myocardial oscillators at the level of the proteome and transcriptome, the primary goal of this review is to assess the molecular mechanisms linking disrupted biological rhythms to heart health, with a focus on core clock genes like BMAL1 and cardiac troponin I (cTnI) as a myocardial biomarker.

MAJOR FINDINGS

Circadian misalignment can lead to cognitive decline, metabolic dysfunction, and immune disruption, all of which elevate CVD risk. BMAL1 has a key role in maintaining cardiovascular integrity, with its dysfunction associated with hypertension, arrhythmias, and myocardial injury. Additionally, disrupted sleep patterns influence the expression of clock genes, potentially leading to altered heart function and elevated levels of cardiac biomarkers like troponin.

CONCLUSION

Circadian misalignment poses significant CVD risks, particularly for older workers. Future research should investigate how the expression of central and peripheral clock genes, as well as cardiac biomarkers is affected by shift work, especially in older individuals. Behavioral interventions such as chronotherapy, light therapy, and scheduled evening sleep may help mitigate these risks, but more studies are needed to assess their long-term effectiveness.

Exploring the Causal Relationship Between Migraine and Insomnia Through Bidirectional Two-Sample Mendelian Randomization: A Bidirectional Causal Relationship

Introduction

The intricate relationship between migraine and insomnia has been a subject of great interest due to its complex mechanisms. Despite extensive research, understanding the causal link between these conditions remains a challenge.

Material and Methods

This study employs a bidirectional Mendelian randomization approach to investigate the causal relationship between migraine and insomnia. Risk loci for both conditions were derived from large-scale Genome-Wide Association Studies (GWAS). The primary method of Mendelian Randomization utilized in this study is the Inverse Variance Weighted (IVW) method.

Results

Our findings indicate a bidirectional causal relationship between migraine and insomnia. In the discovery set, migraine had a significant effect on insomnia (OR=1.02, 95% CI=1.02 (1.01-1.03), PIVW=5.30E-04). However, this effect was not confirmed in the validation set (OR=1.03, 95% CI=1.03 (0.87-1.21), PIVW=0.77). Insomnia also had a significant effect on migraine (OR=1.02, 95% CI=1.02 (0.01-1.03), PIVW=2.67E-08), and this effect was validated in the validation set (OR=2.30, 95% CI=2.30 (1.60-3.30), PIVW=5.78E-06).

Conclusion

This study provides meaningful insights into the bidirectional causality between migraine and insomnia, highlighting a complex interplay between these conditions. While our findings advance the understanding of the relationship between migraine and insomnia, they also open up new avenues for further research. The results underscore the need for considering both conditions in clinical and therapeutic strategies.

Incidence of adverse cardiovascular events in patients with insomnia: A systematic review and meta-analysis of real-world data

Insomnia is a prevalent sleeping disorder associated with increasing cardiovascular (CV) mortality and morbidity. However, data incorporating recent clinical studies evaluating these outcomes is scarce. Hence, we aimed to investigate the association of insomnia with CV mortality, myocardial infarction (MI), all-cause mortality, and incidence of CV disease by conducting the first-ever meta-analysis of real-world data evaluating these CV outcomes. MEDLINE and Scopus databases were queried till August 2022 to identify studies comparing prespecified outcomes in patients with and without insomnia. The primary outcomes were CV mortality and myocardial infarction, while secondary outcomes included all-cause mortality, and CV-disease incidence. All data were pooled using an inverse-variance weighted random-effects model, and results were reported as relative risks (RRs) and p-values. 21 studies were analyzed. Risks for CV mortality and MI were significantly higher in patients with insomnia (RR 1.53, p<0.01, and RR 1.48, p = 0.03, respectively). The risk for all-cause mortality and CV disease incidence was also significantly higher in insomnia patients (RR 1.14, p = 0.03, and RR 1.31, p<0.01, respectively). Individuals with insomnia experience a higher risk of long-term mortality, MI, and incidence of CV disease.

Association between insomnia phenotypes and subclinical myocardial injury: the Multi-Ethnic Study of Atherosclerosis

STUDY OBJECTIVES

To assess whether the association between insomnia and subclinical myocardial injury, as measured by cardiac troponin T (cTnT), differs across insomnia phenotypes.

METHODS

We measured cTnT in 2188 participants in the Multi-Ethnic Study of Atherosclerosis study who had completed sleep questionnaires and undergone unattended polysomnography (PSG) and 7-day actigraphy. Insomnia symptoms were defined as reporting at least one of the following ≥5 nights/week over the past 4 weeks: trouble falling asleep, waking up several times a night, having trouble getting back to sleep after waking up too early, or taking sleeping pills to help falling asleep. Obstructive sleep apnea (OSA) was defined as an apnea-hypopnea index (AHI >15 events/h). Participants were classified into insomnia phenotypes, including comorbid insomnia and OSA (COMISA) and insomnia associated with actigraphy-estimated short sleep (<6 h) or sleep fragmentation.

RESULTS

The mean age was 68.8 (SD 9.2) years, 53.6% were male. In total, 47.8% met threshold levels for insomnia symptoms, and 43.1% had an AHI >15. In adjusted linear regression models COMISA (β 0.08 [standard error (SE) 0.03], p < .01) and insomnia with short sleep duration (β 0.07 [SE 0.03], p < .05) were each associated with higher cTnT compared to a reference group with no insomnia. Insomnia with fragmented sleep (β 0.03 [SE 0.02]) was not associated with higher cTnT (p > .05) in adjusted analyses. OSA was associated with higher cTnT (β 0.09 [SE 0.03], p < .01) in adjusted models.

CONCLUSIONS

COMISA and insomnia with short sleep duration, but not insomnia symptoms alone or fragmented sleep, were associated with increased circulating cTnT in older adults.

Novel oxygen desaturation parameters are associated with cardiac troponin I: Data from the Akershus Sleep Apnea Project

Novel diagnostic markers for obstructive sleep apnea beyond the apnea-hypopnea index (AHI) have been introduced. There are no studies on their association with markers of subclinical myocardial injury. We assessed the association between novel desaturation parameters and elevated cardiac troponin I and T. Participants with polysomnography (498) from the Akershus Sleep Apnea study were divided into normal and elevated biomarker groups based on sex-specific concentration thresholds (cardiac troponin I: ≥4 ng/L for women, ≥6 ng/L for men; and cardiac troponin T: ≥7 ng/L for women, ≥8 ng/L for men). Severity of obstructive sleep apnea was evaluated with the AHI, oxygen desaturation index, total sleep time with oxygen saturation below 90% (T90), lowest oxygen saturation (Min SpO₂ %), and novel oxygen desaturation parameters: desaturation duration and desaturation severity. How the AHI and novel desaturation parameters predicted elevated cardiac troponin I and cardiac troponin T levels was assessed by the area under the curve (AUC). Based on multivariable-adjusted linear regression, the AHI (β = 0.004, p = 0.012), desaturation duration (β = 0.007, p = 0.004), and desaturation severity (β = 0.147, p = 0.002) were associated with cardiac troponin I levels but not cardiac troponin T. T90 was associated with cardiac troponin I (β = 0.006, p = 0.009) and cardiac troponin T (β = 0.005, p = 0.007). The AUC for the AHI 0.592 (standard error 0.043) was not significantly different from the AUC of T90 (SD 0.640, p = 0.08), desaturation duration 0.609 (SD 0.044, p = 0.42) or desaturation severity 0.616 (SD 0.043, p = 0.26) in predicting myocardial injury as assessed by cardiac troponin I. Oxygen desaturation parameters and the AHI were associated with cardiac troponin I levels but not cardiac troponin T levels. Novel oxygen desaturation parameters did not improve the prediction of subclinical myocardial injury compared to the AHI.