People who have chronic insomnia are at a greater risk of dying, according to a new study that took place over 20 years.
At the University of Arizona College of Medicine – Tucson, researchers followed 1,409 adults with various levels of insomnia who were participants in the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD). The study, which began in 1972, had followup surveys until 1996 and they followed up mortality in the subjects until 2011. In its entirety, the stud took place over 38 years.
Researchers collected blood and serum samples from participants and preserved them by freezing in 1972 and at subsequent points in time. Participants were asked about sleep in two surveys done between 1984 and 1985 and against between 1990 and 1992.
Participants were considered to have persistent insomnia if they had regular trouble sleeping in both sets of surveys; if they had insomnia in either survey, they were considered to have “intermittent” insomnia. If they had no insomnia in either survey, they were considered to have “never” insomnia.
Those who had persistent insomnia were at more than 50 percent greater risk of dying during the study compared to participants with no insomnia.
“We hypothesized that insomnia that was persistent over eight years, rather than intermittent insomnia, was associated with death independent of the effects of sedatives, opportunity for sleep [to distinguish it from sleep deprivation], and other confounding factors in a representative sample of the general adult community,” explains lead investigator Sairam Parthasarathy, MD, associate professor of medicine at the University of Arizona College of Medicine-Tucson and director of the Center for Sleep Disorders at the University of Arizona Medical Center–University Campus. “An enhanced understanding of the association between persistence of insomnia and death would inform treatment of the ‘at-risk’ population.”
After they took into account certain variables such as age, sex, body weight, and smoking, subjects with persistent insomnia were 58 percent more likely to die during the study than subjects with no insomnia. Death was related to cardiovascular problems and not cancer. Subjects who died and who had persistent insomnia also were more likely to have higher levels of C-reactive protein, a protein in blood that is elevated in people who are more likely to have coronary artery disease and other types of inflammation, and is a sign of early mortality.
Participants who had intermittent insomnia also had an increased risk of death, but when the researchers looked at variables such as body mass index, smoking status, and physical activity, they found the excess risk was not present.