An association among persistent insomnia, inflammation and mortality has been found by a University of Arizona research team led by Arizona Respiratory Center faculty members Dr. Sairam Parthasarathy and Dr. Stefano Guerra.
The team analyzed data from a long-running UA respiratory study, the Tucson Epidemiological Study of Airway Obstructive Disease, which began in 1972 and has followed participants for decades. The data showed that chronic insomnia was associated with higher levels of inflammation in the blood and a 58 percent increase in risk of death.
Insomnia — difficulty falling asleep, staying asleep or waking too early — is a common medical complaint that affects about 20 percent of U.S. adults. Chronic insomnia is estimated to occur in about half of those individuals.
The UA researchers found that, unlike intermittent insomnia, chronic or persistent insomnia that lasted for at least six years was associated with mortality. Moreover, they found that greater levels of inflammation (measured by a biomarker in blood called C-reactive protein) and a steeper rise in such biomarkers of inflammation were associated with the persistence of insomnia and death.
Although other researchers previously have found an association of insomnia with death, whether this association holds true for both chronic and intermittent insomnia remains unknown. Moreover, many underlying mechanisms for why chronic insomnia may lead to death have been suggested but not been shown.
"An enhanced understanding of the association between persistence of insomnia and death would inform treatment of the at-risk population," said Parthasarathy, lead author of the study. "We found that participants with persistent insomnia were at increased risk of dying due to heart and lung conditions independent of the effects of hypnotics, opportunity for sleep (as distinguished from sleep deprivation), sex, age and other known confounding factors."
Said Guerra, the senior author for the study: "Although there were higher levels of inflammation and steeper rises in inflammation in individuals with persistent insomnia when compared to those with intermittent or no insomnia, more research into other pathways by which persistent insomnia may lead to increased mortality needs to be explored. Such biomarker-based research could potentially help advance precision science in predicting future clinical outcomes in patients with insomnia.”
The study, “Persistent Insomnia Is Associated With Mortality Risk,” has been published online in the American Journal of Medicine (www.amjmed.com/article/S0002-9343(14)00914-0/abstract).
Parthasarathy is associate professor of medicine in the Division of Pulmonary, Allergy, Critical Care and Sleep Medicine of the Department of Medicine, UA College of Medicine – Tucson; medical director of the Center for Sleep Disorders at the UA Medical Center-University Campus; associate director of Sleep and Circadian Sciences at the Arizona Respiratory Center; and program director of the Sleep Medicine Fellowship Program.
Guerra is research associate professor of medicine in the Division of Pulmonary, Allergy, Critical Care and Sleep Medicine of the Department of Medicine, UA College of Medicine – Tucson. He also holds appointments in the UA Mel and Enid Zuckerman College of Public Health and the UA College of Pharmacy’s Southwest Environmental Health Sciences Center, is an associate member of the UA Cancer Center, and is affiliated with the CREAL Centre and Universitat Pompeu Fabra in Barcelona, Spain.
In addition to Parthasarathy and Guerra, researchers who contributed to the study included Dr. Fernando Martinez, director of the Arizona Respiratory Center and director of the UA BIO5 Institute, Regents’ Professor, and Swift-McNear Professor of Pediatrics; and Arizona Respiratory Center members Monica Vasquez, biostatistician; Marilyn Halonen, UA professor emerita of pharmacology; Dr. Stuart Quan, UA professor emeritus of medicine and Gerald E. McGinnis Professor of Sleep Medicine, Harvard Medical School, Boston; and Richard Bootzin, UA professor of psychology and psychiatry, and member of the UA Evelyn F. McKnight Brain Institute.