Roughly one in three American adults – an estimated 83.7 million people – have obstructive sleep apnea, and the majority don’t know it. A separate study tracking nearly a million U.S. veterans over two decades just revealed something that puts that statistic in an entirely different light: if you also have insomnia, your heart disease risk doesn’t just add up. It multiplies.
The combination of insomnia and obstructive sleep apnea has a clinical name – COMISA, short for comorbid insomnia and obstructive sleep apnea. Most doctors still treat these as separate problems, often missing one while managing the other. But researchers from Yale School of Medicine who spent years following post-9/11 veterans found that having both conditions at once creates something far more dangerous than either disorder on its own. The sleep heart disease risk associated with this combination was more than three times that seen in people with neither condition.
Among the nearly one million participants in that study, 14% had COMISA, 13% had insomnia alone, and 21% had sleep apnea alone. That means in a room of 100 people who have been flagged for any kind of sleep disorder, nearly half have more than one. And the most dangerous combination is one that most people have never heard of.
What the Yale Study Actually Found
Researchers from Yale School of Medicine analyzed health data from nearly one million post-9/11 U.S. veterans, finding that the overlap of insomnia and sleep apnea – COMISA – was linked to a significantly increased risk of both high blood pressure and cardiovascular disease. The study, published in the Journal of the American Heart Association, examined sleep problems as a powerful yet frequently overlooked factor in heart health.
The study included 984,946 veterans followed for up to 20 years, with researchers comparing those with no sleep disorders, insomnia only, sleep apnea only, and COMISA. Large observational studies don’t always survive when researchers control for age, weight, smoking history, and other cardiovascular risk factors. This one did. Having both insomnia and obstructive sleep apnea was associated with more than triple the risk of developing cardiovascular disease.
The researchers also found that even when insomnia or sleep apnea occurred alone, each was linked to increased cardiovascular risk – but the jump in risk when both were present was substantially larger than either condition added individually. The study analyzed results separately for men and women and found that the combined sleep disorder increased risk in both sexes.
High blood pressure was another significant finding. Adults diagnosed with both insomnia and obstructive sleep apnea faced substantially higher risks of hypertension compared to those with either condition in isolation, with the Journal of the American Heart Association study documenting more than a two-fold increase in incident hypertension among the COMISA group. Hypertension, for its part, is one of the leading drivers of heart attack and stroke – so even the blood pressure finding alone would be clinically significant.
Why These Two Conditions Are So Much Worse Together
During healthy sleep, heart rate and blood pressure naturally dip, giving the cardiovascular system a chance to rest and repair. When sleep is fragmented or disrupted, that recovery doesn’t happen the way it should.
Sleep apnea causes intermittent drops in oxygen levels, which stresses the heart and blood vessels. During an apneic episode – a moment when the airway collapses and breathing stops – oxygen saturation in the blood can fall sharply. A scientific statement published in the Journal of the American College of Cardiology found that during apneic episodes, oxygen saturation can drop to 60% or lower, a level that triggers the nervous system’s fight-or-flight response. Specifically, these repeated oxygen drops prompt what’s known as sympathetic activation and vasoconstriction – meaning the nervous system revs up, blood vessels tighten, and the heart is forced to work harder, repeatedly, throughout the night. The same research noted that this pattern resembles ischemia-reperfusion injury, the kind of cellular damage seen when blood supply is cut off and then restored, generating harmful reactive oxygen species (free radicals that damage tissues).
Insomnia, meanwhile, keeps the body in a state of heightened alertness, triggering inflammation and chronic stress responses. People with insomnia often have chronically elevated levels of cortisol and inflammatory markers – the same physiological signatures associated with heart disease risk over time. The body stays in a low-grade emergency state night after night, never fully standing down.
Put both processes together and the cardiovascular system gets hammered from two directions simultaneously: oxygen deprivation from the apnea side, and chronic stress activation from the insomnia side. Neither allows for the overnight recovery that keeps the heart healthy long-term.
A 2026 study published in the journal Sleep, using the TriNetX U.S. Collaborative Network, offered additional support. COMISA was associated with higher 10-year risks of cerebrovascular disease, arrhythmias, inflammatory and ischemic heart disease, and thrombotic disorders compared to sleep apnea alone – suggesting the damage extends well beyond the heart itself.
How Common Is This, Really?
Both conditions are far more widespread than most people realize, which is why the scale of the COMISA problem is easy to underestimate.
An estimated 83.7 million adults in the United States have obstructive sleep apnea as of 2024, according to a 2025 systematic review published in Respiratory Medicine. That’s roughly one in three American adults over age 20. Critically, the vast majority are undiagnosed. Symptoms like snoring, waking with headaches, or feeling unrested despite a full night’s sleep are often attributed to stress, aging, or lifestyle rather than a medical condition with serious consequences.
On the insomnia side, the CDC’s 2024 National Health Interview Survey found that 15.4% of U.S. adults had trouble falling asleep most days, and 18.1% reported trouble staying asleep – figures that represent tens of millions of people experiencing persistent sleep difficulties. Many of them likely have no idea their insomnia may be occurring alongside undiagnosed sleep apnea.
Although these disorders are often treated separately, many people experience both at the same time. That gap in clinical practice is part of what makes the Yale findings so important. Screening for one condition without considering the other may leave a patient’s actual risk substantially underestimated – and undertreated.
What to Do If You Suspect COMISA
Researchers behind the Yale study emphasized that they wanted to know whether COMISA mattered early in the cardiovascular risk trajectory, rather than decades later when disease is already established. That framing carries a practical message: the time to address these conditions is before damage accumulates, not after a cardiac event.
Diagnosis is the first step. Sleep apnea is typically identified through a polysomnography study (a monitored overnight sleep test) or a home sleep apnea test. Insomnia is usually diagnosed clinically, based on reported symptoms and their duration. Because the two conditions share some overlapping presentations – fragmented sleep, fatigue, poor concentration – a comprehensive sleep evaluation is important for anyone who suspects more than one issue is at play.
For insomnia, cognitive behavioral therapy for insomnia (CBT-I) is the established first-line treatment. CBT-I is a structured, non-medication approach that targets the thoughts and behaviors that perpetuate sleeplessness. It typically involves sleep restriction therapy, stimulus control, and cognitive restructuring – and it has a strong evidence base, outperforming sleeping pills in long-term outcomes for most patients.
For sleep apnea, CPAP therapy remains the most effective treatment. A 2024 analysis published in BMC Sleep Medicine confirmed that CPAP therapy significantly helps treat patients. CPAP works by delivering a constant stream of pressurized air through a mask, keeping the airway open throughout the night and preventing the oxygen drops that drive cardiovascular strain. Adherence can be a challenge for some patients, but early support and mask fitting adjustments substantially improve long-term compliance.
For people with COMISA, the emerging clinical position is that treating only one condition leaves too much risk on the table. Researchers advocate for assessing sleep as routinely as other cardiovascular risk factors and considering insomnia and sleep apnea together. Some sleep specialists now offer combined treatment protocols that address both simultaneously, particularly for patients who’ve struggled with CPAP – since untreated insomnia can make CPAP adherence harder, and untreated sleep apnea can make insomnia worse.
If you’re already exploring the connection between sleep quality and heart disease, the COMISA research adds a critical layer: it’s not just about how many hours you sleep, but about the quality and architecture of that sleep, and whether two overlapping disorders are silently compounding each other.
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What to Do Now
Sleep disorders are not soft problems. They are modifiable cardiovascular risk factors – measurable, treatable, and increasingly shown to rival blood pressure and cholesterol in their long-term impact on heart health.
Investigators from the Yale team emphasize that sleep disorders should be addressed early in the cardiovascular risk trajectory, and that sleep health should be assessed as routinely as other cardiovascular risk factors. That means asking your doctor about sleep at your next checkup, not just at a dedicated sleep clinic. If you snore, wake repeatedly through the night, lie awake for more than 30 minutes before falling asleep most nights, or feel unrestored most mornings, bring those symptoms up together – not as separate complaints, but as a constellation that warrants evaluation for COMISA.
The COMISA finding isn’t just a statistic about veterans. By paying attention to these treatable risk factors sooner, clinicians may be able to change the trajectory of cardiovascular disease – and the same logic applies to patients who take their sleep symptoms seriously before a cardiologist has to.
Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis, or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.
AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.
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