Insomnia Looks Causal for Heart Disease, but Treatment Benefit Remains Unproven

Up to 1 in 3 adults experiences insomnia at some point in life, and for many of them, the sleep disorder may not simply coexist with heart disease—it may help contribute to it.¹

An Overlooked Cardiovascular Risk Factor

Cardiovascular disease (CVD) risk models have mostly absorbed insomnia into a broader sleep-duration metric rather than treating it as a target of its own. The American Heart Association added sleep to its Life's Essential 8 checklist in 2022, but sleep duration covaries with insomnia, complicating efforts to isolate the disorder's own contribution to heart risk, since it often overlaps with obstructive sleep apnea.

As many as half of adults experience short-term insomnia at some point, and roughly 1 in 10 has chronic insomnia, a pattern the CDC links to elevated blood pressure and cardiovascular disease.² Chronic insomnia can persist for years and grows more common with age, extending beyond disrupted sleep into impaired concentration, memory, mood, and next-day functioning.

Weighing Causality With Bradford Hill Criteria

To test whether the insomnia-CVD association reflects more than correlation, the review's authors applied the Bradford Hill criteria, a long-standing framework for judging causality in observational research.¹ They searched MEDLINE from inception through August 1, 2025, pairing insomnia with terms for CVD, heart failure, myocardial infarction, stroke, and other cardiovascular end points, limiting inclusion to peer-reviewed, English-language studies of adults 18 years and older.

The resulting evidence spans dozens of meta-analyses, prospective and retrospective cohorts, Mendelian randomization analyses, and randomized controlled trials, with study sizes ranging from dozens of participants to more than 2.5 million. Throughout, the authors distinguished studies that used a formal clinical diagnosis of insomnia from those relying on self-reported symptoms, the more common approach in large analyses.

The association held up consistently across designs. A meta-analysis of real-world data found individuals with insomnia symptoms carried a 53% higher risk of cardiovascular mortality (relative risk [RR], 1.53; P < .01), a 48% higher risk of myocardial infarction (RR, 1.48; P < .03), and a 31% higher risk of incident CVD (RR, 1.31; P < .01) compared with those without sleep disorders. A separate meta-analysis of 13 prospective cohorts totaling 122,501 subjects found a 45% increased risk of developing or dying from CVD over 3 to 20 years of follow-up.

The relationship also showed a biological gradient, one of the Bradford Hill criteria, with risk climbing alongside symptom count. Among more than 487,000 adults, cardiovascular risk rose from 7% with 1 insomnia symptom to 18% with 3 (HR, 1.07 to 1.18); among more than 12,700 middle-aged and older adults, the risk of incident heart failure climbed from 22% with 1 symptom to 80% with 4 (HR, 1.22 to 1.80). Mendelian randomization studies, which use genetic variants to limit confounding, extended the case for causality: in analyses of more than 2 million participants, genetic liability to insomnia was tied to ischemic stroke, coronary artery disease, heart failure, and type 2 diabetes.

“Well-powered, rigorously designed trials targeting patients with clinically defined insomnia are needed to determine whether effective insomnia treatment can meaningfully reduce cardiovascular risk and inform future prevention strategies,” the researchers wrote.

Treatment Has Not Yet Proven It Lowers Cardiovascular Risk

Proposed biological pathways, including hypothalamic-pituitary-adrenal axis activation, heightened sympathetic activity, blunted nighttime blood pressure dipping, and low-grade inflammation, plausibly link poor sleep to hypertension and myocardial injury. But if insomnia truly drives cardiovascular risk, treating it should improve outcomes, and evidence for that reversibility criterion is thin. Three randomized controlled trials have tested whether cognitive behavioral therapy for insomnia, the most effective nonpharmacologic treatment, lowers blood pressure; none found a significant effect, and each was hampered by small samples, high dropout, or loosened enrollment criteria that included participants without high blood pressure.

Pharmacologic options raised safety concerns, too. In a Women's Health Initiative analysis of postmenopausal women followed for 14 years, nonbenzodiazepine Z-drug use was associated with an increased risk of death and CVD, though the authors cautioned that residual confounding and indication bias complicate that finding. In a Veterans Affairs cohort of more than 16,000 patients with newly diagnosed insomnia, hypnotic use was linked to higher rates of major adverse cardiovascular events, though not nonfatal events specifically, and among Japanese patients hospitalized for heart failure, benzodiazepine use independently predicted rehospitalization (HR, 1.53; 95% CI, 1.03-2.28).

As a narrative review rather than a systematic one, the analysis cannot offer a full accounting of every relevant study or confirm the reversibility criterion outright, the authors acknowledged. A few of the studies it draws on adjusted for comorbid obstructive sleep apnea, which compounds cardiovascular risk when present alongside insomnia.

For clinicians and payers, the message outruns the proof: insomnia is common, plausibly causal for cardiovascular disease, and still routinely treated with therapies unproven to lower that risk. Until adequately powered trials enroll patients with a formal insomnia diagnosis and track hard cardiovascular end points, the safer course favors cognitive behavioral therapy over hypnotics in patients at elevated cardiovascular risk.

References

1. Pengo MF, Javaheri S, Maiolino G, Redline S, Lombardi C. Insomnia and cardiovascular disease: untangling a complex relationship. J Sleep Res. 2026;35:e70299. doi:10.1111/jsr.70299

2. Centers for Disease Control and Prevention. About sleep and your heart health. CDC. Accessed August 26, 2026. https://www.cdc.gov/heart-disease/about/sleep-and-heart-health.html