Insomnia plus sleep apnea linked to 78% higher heart attack and stroke risk in 1,860 Swiss adults

Among middle-aged and older adults in Lausanne, Switzerland, those with both insomnia symptoms and sleep apnea had an estimated 12.9% risk of a heart attack, stroke or other serious cardiovascular event over eight years. That compared with 8.1% in the reference group of adults with neither, once age, weight, blood pressure and other known risks were allowed for: roughly 13 in 100 against 8 in 100.

The figures come from a study published on September 28 in eClinicalMedicine by sleep researchers at Lausanne University Hospital, led by Geoffroy Solelhac, Theo Imler and Raphael Heinzer. In relative terms, the rate of heart attacks and strokes was 78% higher with both conditions. The result stands out for what happened when the two conditions were pulled apart: participants with only insomnia symptoms, or only sleep apnea, did not show a clear rise in risk. The excess sat with the combination, which sleep doctors call COMISA, short for comorbid insomnia and sleep apnea.

Two common sleep problems that often arrive together

Obstructive sleep apnea is a breathing disorder in which the upper airway keeps closing, fully or partly, during sleep. A 2021 scientific statement from the American Heart Association describes repeated airway obstructive events, resulting in intermittent hypoxemia, meaning drops in blood oxygen, along with surges in the nervous system and broken sleep. The statement estimates that about 34% and 17% of middle-aged men and women meet the diagnostic criteria, and says the condition is often underrecognized and undertreated in cardiovascular practice.

Insomnia is the more familiar complaint: trouble getting to sleep, staying asleep, or waking too early. It might seem like the opposite of apnea, which tends to bring daytime sleepiness, yet the two overlap heavily. The Lausanne authors cite studies in which up to half of people with apnea report significant insomnia symptoms, and vice versa.

Each condition on its own has been tied to heart disease, which is why researchers began to ask whether having both carries extra risk. Yet only a few longitudinal studies have examined heart events in people with both. A search of the literature by the Swiss team turned up four, and only two of those measured apnea with polysomnography, the full overnight sleep recording that tracks breathing, oxygen and brain waves. The others leaned on diagnosis codes in medical records. The Lausanne study adds to that small set, with an overnight recording for everyone and participants drawn from the general population.

How the Lausanne study measured sleep and heart events

The participants came from CoLaus, a long-running study of Lausanne adults, randomly selected from 35- to 75-year-old residents using the city’s population register. Between 2009 and 2013, 1,860 of them had a full-night sleep recording and filled in a standard sleep questionnaire. Their median age was 56, and just over half were women.

From the overnight data, the team counted pauses and shallow breaths per hour of sleep. Fifteen or more an hour counted as moderate-to-severe sleep apnea, and 650 people, about a third, met it. From the questionnaire, anyone who had trouble falling asleep within 30 minutes, or woke in the night or early morning, at least three times a week over the past month counted as having insomnia symptoms. That applied to 606 people, also about a third. Everyone then fell into one of four groups: neither condition, insomnia only, apnea only, or both.

The researchers then followed them for a median of almost eight years. Heart attacks, strokes, other coronary heart disease and cardiovascular deaths were found through participants’ reports, medical records, hospital databases and death registers, and each event was adjudicated by a local expert committee of internists, cardiologists and neurologists. That check makes it less likely that a misfiled record was counted as a heart attack.

The analysis allowed for age, sex, weight, alcohol, smoking, previous heart events, high blood pressure, diabetes and cholesterol problems. That matters because those with both sleep problems were older, more frequently men, had a higher BMI and had more heart-related illness to begin with than those with neither.

Heart attacks and strokes in each sleep group

Looked at on its own, sleep apnea behaved as decades of research would predict. Counted irrespective of insomnia symptoms, it went with a rate of new heart events 73% higher than in participants without apnea, after adjustment. That figure, though, includes the people who had insomnia symptoms as well as apnea.

Splitting the people with apnea by insomnia symptoms changed the picture. Participants with apnea but no insomnia symptoms had a rate about a third higher than those with neither, a difference small enough that it could have been chance. Those with insomnia symptoms but no apnea had a lower rate, but that estimate was also uncertain, and the authors warn against reading it as a true protective effect. Only those with both had a clearly raised rate, 78% above the reference.

A statistical test asked whether having both carried more risk than the two separate effects would predict, and it found that it did: the rate with both was a little over twice what the separate effects implied, though with a wide range around that figure. On the authors’ reading, having both may confer a higher cardiovascular risk than either one does alone.

The result held in several checks. It stayed when the team left out anyone who already had heart disease at the start, when it set aside those who began using a breathing machine during follow-up, and under three stricter definitions of insomnia. The link was stronger when insomnia was defined to include regular use of sleeping pills, which the authors suggest may mark more persistent or severe insomnia.

One check went the other way. After excluding cerebrovascular events from the composite outcome, which removed 35 strokes and related cases, the link between the combination and the remaining heart problems was no longer clear. So a good share of the excess risk came from strokes, and the study had too few of them to examine strokes on their own.

Why insomnia might add to sleep apnea’s strain on the heart and arteries

The study cannot show a mechanism, but the authors sketch two that may feed each other. Insomnia can keep the body on heightened alert, with more stress-hormone activity and a busier “fight or flight” nervous system. Apnea adds repeated falls in oxygen, swings in pressure inside the chest and inflammation. Their suggestion is that insomnia-related hyperarousal and sleep fragmentation may interact with the oxygen drops of apnea.

The breathing measurements did not explain the difference. Participants with apnea alone and those with both conditions had similarly severe apnea by every standard index. What set the combination apart was a lower proportion of slow wave sleep, the deepest stage of sleep, than either the insomnia-only or the apnea-only group.

The authors also offer a speculative link to one of the field’s most discussed disappointments. In the SAVE trial, published in 2016, researchers took 2,717 adults with moderate-to-severe sleep apnea and existing heart or blood vessel disease and randomly assigned them to receive CPAP treatment plus usual care, or usual care alone. CPAP is the breathing machine worn at night. After almost four years, CPAP did not prevent cardiovascular events: 17.0% of the CPAP group had one, against 15.4% of the usual-care group, a difference that could have been chance. The Lausanne team suggests that the extra risk carried by insomnia may help explain why CPAP has disappointed in preventing cardiovascular disease in randomized controlled trials. Nobody has tested that.

Other studies of insomnia with sleep apnea are mixed

The largest earlier study, of US veterans, partly agrees with the Lausanne result. Among nearly a million post-9/11 veterans followed through their health records, having both diagnoses carried the greatest risk of hypertension and of cardiovascular disease. Unlike in Lausanne, insomnia alone and apnea alone were each linked to higher risk too. In China, a study of 868 elderly patients with sleep apnea found that adding insomnia went with more major heart events, mainly hospital stays for unstable angina, a warning form of chest pain.

Other studies saw the link fade once other illnesses were accounted for. In 3,951 patients from US sleep clinics, the combination was tied to more heart attacks and strokes, but not after further adjustment for comorbidities, the other illnesses patients had. A 2026 scoping review by French researchers covered 17 studies. It found that once other risk factors were taken into account, large long-term cohorts showed no significant excess risk of new heart problems. The reviewers called the results mixed and limited by considerable methodological heterogeneity, meaning the studies defined and measured the two conditions in very different ways.

Against that background, the new study’s strength is measurement: an overnight recording for everyone and specialist-checked events, in adults drawn from the general population instead of a sleep clinic.

Gaps in the Lausanne insomnia and sleep apnea study

This is an observational study, so it shows that the combination went with more heart attacks and strokes, without showing that it caused them. The authors adjusted for many risk factors but write that residual confounding cannot be entirely excluded, meaning that some unmeasured difference between the groups could account for part of the result.

The range around the main estimate is wide, from 9% higher to nearly three times as high, which reflects a modest number of heart attacks and strokes behind it. The finding also leaned on strokes, as the check above showed.

Insomnia was judged from a single questionnaire at the start. That questionnaire does not fully align with ICSD-3 or DSM-5 diagnostic criteria, the formal definitions used by sleep doctors and psychiatrists, so the authors say their results should not be generalized to patients with chronic insomnia. Because insomnia symptoms were assessed at baseline only, some people’s sleep will have changed over the following eight years.

Everyone lived in one Swiss city, and the study does not show whether the pattern holds elsewhere or in younger adults.

What the results mean for people with insomnia and sleep apnea

The study does not test any treatment. “Patients with COMISA may represent a particularly vulnerable phenotype with increased cardiovascular risk,” the authors write. They note that cognitive behavioral therapy for insomnia, a structured talking treatment, has been shown to improve CPAP adherence, so that patients wear the machine more. Whether treating both conditions together lowers heart risk is unknown, and the authors call for studies to find out. How sleep problems and heart risk are weighed for any one person is assessed by their doctor.

For now the Lausanne data single out people with both insomnia and sleep apnea as having more heart attacks and strokes, in one city and on one wide estimate.