Insomnia and obstructive sleep apnea are often treated as separate problems. A large new study suggests that when the two conditions overlap — a pattern researchers call COMISA — the cardiovascular consequences are far worse than either disorder alone.
The study, published in the Journal of the American Heart Association, analyzed data from 937,598 post-9/11 U.S. veterans over two decades and found that those with both conditions had nearly four times the risk of developing cardiovascular disease.
The Numbers
The findings are striking. Using time-varying Cox proportional hazard models adjusted for demographics, behavioral factors, and clinical history, the researchers found:
- Veterans with both insomnia and sleep apnea (COMISA) had a 3.81 times greater risk of cardiovascular disease (95% CI, 3.64–3.99) and a 2.43 times greater risk of hypertension (95% CI, 2.36–2.50)
- Sleep apnea alone was associated with a 2.62 to 3.32 times greater CVD risk and 2.00 to 2.26 times greater hypertension risk
- Insomnia alone carried a more modest but still elevated risk: 1.36 to 1.37 times for CVD and 1.27 to 1.44 times for hypertension
The pattern was consistent across both sexes. Women with COMISA had a 3.44 times greater CVD risk (95% CI, 2.98–3.98), while men faced a 3.81 times greater risk (95% CI, 3.63–4.00).
More Than the Sum of Their Parts
What makes this study significant is not just that each condition carries risk on its own — that has been established in prior research. It's that the combination appears to create a compounding effect that exceeds what you would expect from adding the two together.
"These conditions don't just coexist politely," said lead author Allison E. Gaffey, PhD, of Yale School of Medicine. "Treating one while ignoring the other is a bit like bailing water out of a boat without fixing the leak."
Obstructive sleep apnea causes repeated breathing pauses that drop oxygen levels and trigger surges in blood pressure and stress hormones throughout the night. Insomnia fragments sleep in a different way — through difficulty falling or staying asleep, leading to chronic sleep deprivation and heightened nervous system arousal. Together, the two conditions may create a cycle where each makes the other harder to treat and the cardiovascular system bears the compounded strain.
Why It Matters Early
The study focused on relatively young veterans — the median age was 41 — deliberately targeting a population early in their cardiovascular risk trajectory, before conditions like hypertension and heart disease have fully developed.
"We spend enormous time managing cardiovascular disease downstream, but far less addressing upstream modifiable risk factors," Gaffey noted. The researchers argue that catching and treating sleep disorders earlier could prevent cardiovascular disease rather than simply managing it after the fact.
Senior author Andrey Zinchuk, MD, MHS, emphasized the broader point: "Sleep touches every single part of our existence. Oftentimes, it is neglected even though it has such an important impact on our lives."
What This Means for Patients
An estimated 30 to 50 million Americans have obstructive sleep apnea, and roughly 1 in 3 adults report insomnia symptoms. The overlap is common — studies suggest that 30% to 60% of people with one condition also have the other.
Yet in clinical practice, the two are typically evaluated and treated by different specialists. Sleep apnea is diagnosed through sleep studies and managed with CPAP or newer alternatives, while insomnia is often addressed through cognitive behavioral therapy or medication — if it is addressed at all.
The Yale findings reinforce a growing consensus that sleep health should be assessed as routinely as cholesterol and blood pressure. For the millions of people who lie awake at night and struggle to breathe during the sleep they do get, treating both problems together may be critical to protecting their hearts.
