New Study Finds Insomnia Combined with Sleep Apnea Dramatically Raises Cardiovascular Risk

Most people know sleep apnea is bad for the heart. Plenty of people have heard that chronic insomnia takes a toll on the body. What a major new study makes clear — with a dataset of nearly one million veterans behind it — is that having both conditions simultaneously isn't just slightly worse than having one. It's dramatically more dangerous, in ways that researchers say medicine has significantly underestimated.

The research, published March 1, examined sleep disorder diagnoses and cardiovascular outcomes across a veteran population large enough to generate statistically powerful conclusions. The finding was stark: people diagnosed with both insomnia and sleep apnea faced a substantially elevated risk of serious cardiovascular events compared to those with either condition alone. The combination, scientists concluded, creates a compounding physiological burden that individual diagnoses and their associated risk models don't capture.

Why the Combination Is More Than the Sum of Its Parts

Sleep apnea disrupts cardiovascular function through a specific and well-documented mechanism: repeated episodes of oxygen deprivation during sleep activate the sympathetic nervous system, raise blood pressure, and over time contribute to arterial damage, arrhythmias, and increased risk of heart attack and stroke. The heart is essentially working against an adversarial sleep environment every night.

Insomnia operates through a different but overlapping set of pathways. Difficulty falling or staying asleep elevates cortisol levels, promotes chronic low-grade inflammation, impairs glucose metabolism, and keeps the body in a state of heightened physiological stress. People with insomnia tend to spend more time in lighter sleep stages with less restorative deep sleep, which compounds the recovery deficit.

When both conditions are present simultaneously, the mechanisms reinforce each other. The oxygen disruptions from sleep apnea further fragment already compromised sleep, making insomnia worse. The heightened arousal state from insomnia may increase sensitivity to apnea events and their cardiovascular consequences. The body never gets adequate restoration, and the cumulative stress on the cardiovascular system builds continuously rather than being offset by even partial recovery.

The Scale of the Study and Why It Matters

Sleep research has historically been constrained by sample size. Running sleep studies in laboratory conditions is expensive and logistically intensive, and most community-based studies haven't had the statistical power to examine subgroup combinations like co-occurring sleep disorders with the confidence needed to draw firm clinical conclusions. A dataset of nearly one million people changes that calculus entirely.

The U.S. Department of Veterans Affairs maintains some of the most comprehensive longitudinal health records in the country, which is why veteran populations appear repeatedly in large-scale health research. The tradeoff is that veteran populations skew male and tend to have higher rates of conditions like PTSD, traumatic brain injury, and chronic pain — all of which affect sleep — than the general population. That means the findings are most directly applicable to similar populations, though the underlying physiological mechanisms are universal enough that the implications extend broadly.

Diagnosis Gaps: The Problem of Two Conditions Treated Separately

One of the more sobering implications of the research is what it suggests about how medicine currently handles patients who have both conditions. Sleep apnea and insomnia are typically diagnosed and treated through different clinical pathways. Sleep apnea is primarily managed by sleep medicine specialists and pulmonologists through CPAP therapy or similar interventions. Insomnia is frequently addressed by primary care physicians or psychiatrists, often through behavioral therapy or medication.

A patient seeing different providers for each condition — a common scenario in fragmented healthcare systems — may have neither provider fully accounting for the interaction between the two diagnoses. Risk assessments for cardiovascular disease may not incorporate both conditions together in the way this research suggests they should. The study makes a strong case for a more integrated approach to sleep disorder evaluation, particularly for patients with known cardiovascular risk factors.

Practical Implications for People With Both Diagnoses

For the estimated tens of millions of Americans who have some form of sleep-disordered breathing along with chronic sleep difficulties, the research carries a practical message: don't treat these as separate, lower-priority health issues. The cardiovascular risk associated with the combination is serious enough that it warrants active clinical attention rather than the quiet acceptance that many people with long-term sleep problems tend toward.

CPAP adherence — which is notoriously poor, with many patients abandoning therapy within months — becomes more urgent when the stakes are framed in terms of serious cardiac events rather than just better sleep quality. Behavioral interventions for insomnia, particularly cognitive behavioral therapy for insomnia which has strong clinical evidence behind it, should probably be initiated alongside rather than after sleep apnea treatment in co-occurring cases.

What Comes Next in the Research

The study identifies a risk profile with strong statistical support but doesn't yet answer the intervention question definitively: does successfully treating both conditions together reduce the combined cardiovascular risk to something closer to baseline, or does the elevated risk persist? That's the logical next research question, and it has direct clinical implications for how aggressively treatment should be pursued and what success metrics clinicians should use.

For now, the contribution is already significant. A finding this clear, from a dataset this large, gives clinicians a concrete basis for reframing how they discuss sleep disorder risk with patients who present with both insomnia and sleep apnea. The conversation probably shouldn't start with sleep quality. It should start with the heart.