A genetic predisposition for insomnia was linked to greater odds of heart disease and stroke—but not atrial fibrillation—in a study of more than a million people with or without CVD.
In a research letter published in Circulation this month, Susanna C. Larsson, PhD, and Hugh S. Markus, MD, said their analysis aimed to determine whether the established link between insomnia and heart disease has anything to do with genetics or whether it’s something that could be mitigated with improved sleep patterns.
“Evidence from observational studies indicates that insomnia is associated with an increased risk of cardiovascular disease,” the co-authors wrote. “However, whether the association is causal is unknown because observational studies are hampered by reverse causation bias and residual confounding.”
Larsson and Markus applied Mendelian randomization (MR) to data from 1.3 million people with or without heart disease, pulled from four major CV databases. They looked for a link between insomnia and coronary artery disease (CAD), heart failure, AFib and three types of stroke.
The team identified a genetic correlation between insomnia and CAD, heart failure and stroke, but not between insomnia and atrial fibrillation. When it came to stroke, genetic variants seemed to impact the odds of large artery stroke the most (13% increased risk), followed by small vessel stroke (8% increased risk) and cardioembolic stroke (6% increased risk).
The authors said their findings remained significant even after adjustment for factors like smoking, education and depression, all of which are genetically linked to insomnia.
“This MR study indicates that liability to insomnia is associated with a modest increased risk of CVD,” they wrote. “The association between insomnia and CVD risk may be mediated by increased sympathetic nervous system, systemic inflammation and cardiometabolic risk factors. Previous MR analyses have shown that genetic liability to insomnia is associated with body mass index, waist-to-hip ratio and type 2 diabetes mellitus.”
After graduating from Indiana University-Bloomington with a bachelor’s in journalism, Anicka joined TriMed’s Chicago team in 2017 covering cardiology. Close to her heart is long-form journalism, Pilot G-2 pens, dark chocolate and her dog Harper Lee.