Study: Persistent Insomnia Linked to Higher Risk of Death

Study participants with persistent insomnia had a 58% higher chance of dying than those without insomnia and also had higher levels of inflammation, according to a recent study in the American Journal of Medicine.

“We believe that this is the first study to ‘connect the dots’ between insomnia, inflammation, and death,” says lead investigator Sairam Parthasarathy, MD, associate professor of medicine at the University of Arizona College of Medicine in Tucson.
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“Although the biomarker for inflammation was increasing at a faster rate in those with persistent insomnia, it is unclear if this protein (CRP) mediates the relationship between insomnia and death,” he says.

Previous studies have established links between insomnia and increased risk of premature death, but Parthasarathy and his colleagues wanted to clarify if that risk differed between patients with persistent insomnia and those with intermittent insomnia.

Often linked to specific events like a job interview or stressful situation, intermittent (acute) insomnia has a short duration, while persistent (chronic) insomnia is a long-term pattern of disrupted sleep several nights a week that lasts for months and years.

About 10% of adults in the United States suffer from persistent insomnia, which can result from a number of causes, including shift work, poor sleep habits, and medication use.

Parthasarathy and his team examined data from 1,409 adults who took part in the Tucson Epidemiological Study of Airway Obstructive Disease. Enrolled in 1972, participants were surveyed and examined until 1996, with deaths in the group monitored until 2011.

Based upon questionnaire responses completed between 1984 and 1985 and again between 1990 and 1992, the researchers divided participants into 3 categories:

• Persistent insomnia: insomnia was present in both questionnaires.

• Intermittent insomnia: insomnia was present in either but not both questionnaires.

• Never insomnia: insomnia was not present in either questionnaire.

Of the participants, 18% had intermittent and 9% had persistent insomnia. During the 20-year follow-up period, 318 participants died—118 due to cardiopulmonary disease. Compared to those without insomnia, those with persistent insomnia but not intermittent insomnia had a higher risk of death.

After taking potential confounders into account, results indicated a 58% higher chance of dying in the persistent insomnia group during the study compared to the never insomnia group. The researchers also noted excess deaths in the persistent insomnia group were due to cardiopulmonary factors rather than cancer.

“Sleep is closely tied to the body's immune system,” Parthasarathy says. “When our sleep is poor—as in insomnia—there is an increased risk for inflammation and consequent risks to the heart and lungs.”

Parthasarathy and his colleagues are trying to identify biomarkers in the blood that can predict which individuals are at risk for developing persistent insomnia and which of those are more likely to die.

“This will allow us to target our limited resources preferentially. Moreover, many individuals with insomnia prefer not to receive treatment as they do not want to get dependent on sleeping medications,” Parthasarathy explains. “Such predictive blood tests would advise us as to which one of these individuals are potentially more likely to benefit from therapy as well as to motivate them to get treatment.”

—Colleen Mullarkey

Reference

Parthasarathy S, Vasquez MM, Halonen M, Bootzin R, Quan SF, Martinez FD, Guerra S. Persistent insomnia is associated with mortality risk. Am J Med. 2015 Mar;128(3):268-75.e2.