COMISA associated with uncontrolled hypertension in middle-aged population

Sleep disorders are common, but when two of them occur together, the health consequences may be greater than expected. A recent study by Dr. Mio Kobayashi Frisk and coworkers published in the Annals of the American Thoracic Society suggests that people who experience both insomnia and obstructive sleep apnea (OSA) may face a higher risk of uncontrolled high blood pressure.

Insomnia and OSA are among the most common sleep disorders.

Insomnia involves difficulty falling asleep, staying asleep, or waking up feeling unrefreshed. It affects millions of adults and can significantly reduce quality of life.

OSA, on the other hand, occurs when the airway repeatedly becomes blocked during sleep. This causes breathing pauses, drops in blood oxygen levels, and frequent nighttime awakenings.

Although these conditions are often studied separately, many people experience both at the same time. This combined condition is known as COMISA—short for comorbid insomnia and sleep apnea. To explore this question, researchers analyzed data from the Swedish CArdioPulmonary BioImage Study (SCAPIS), a major population-based health study in Sweden.

The analysis included 3,832 adults aged roughly 50–64 years who underwent extensive health testing, including sleep assessments and blood pressure measurements. Participants completed questionnaires about sleep problems and used a home device that measured breathing during sleep to detect sleep apnea.

Based on these assessments, participants were divided into four groups:

• People without insomnia or sleep apnea
• People with insomnia only
• People with sleep apnea only
• People with both conditions (COMISA)

Researchers then compared how common uncontrolled high blood pressure was across these groups. The combination was the biggest risk. Uncontrolled hypertension was found in:

• 4% of people with neither disorder
• 5% of people with insomnia only
• 9% of people with sleep apnea only
• 2% of people with both conditions (COMISA)

Even after adjusting for factors such as age, body weight, lifestyle, and other health conditions, people with both insomnia and sleep apnea had nearly twice the odds of uncontrolled high blood pressure compared with those without sleep disorders.  In contrast, insomnia alone was not strongly associated with uncontrolled hypertension in this analysis.

Why might sleep disorders affect blood pressure?

Sleep plays a key role in regulating many systems in the body, including the cardiovascular system.

Sleep apnea can repeatedly reduce oxygen levels during the night and trigger brief awakenings. This activates stress responses in the body and can increase sympathetic nervous system activity—essentially keeping the body in a state of “fight or flight”. Over time, these repeated stress responses may contribute to higher blood pressure.

In the study, researchers found that nocturnal hypoxia—periods when blood oxygen levels fall during sleep—appeared to partly explain the relationship between sleep apnea and uncontrolled hypertension. When insomnia occurs at the same time, the overall disruption to sleep may become even more severe, potentially worsening these pathophysiological effects.

Why this matters

High blood pressure is one of the leading risk factors for heart disease, stroke, and premature death worldwide. The findings suggest that sleep health may be an important—and often overlooked—piece of the puzzle.

People who have both insomnia symptoms and sleep apnea may represent a particularly high-risk group that could benefit from targeted treatment. Addressing sleep problems might help improve blood pressure control and reduce long-term cardiovascular risk.

The researchers emphasize that sleep should be viewed as a multidimensional health factor, not just a matter of how many hours someone sleeps. Different sleep disorders can interact with each other, and their combined effects may be stronger than previously recognized. Sleep disorders are not just nighttime problems—they may have serious consequences for long-term health.