Researchers from the University of Arizona have identified a link between persistent insomnia and increased inflammation and mortality.
Lead investigator Sairam Parthasarathy, MD said that they hypothesized that insomnia, which was persistent over 8 years, 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. An enhanced understanding of the association between persistence of insomnia and death would inform treatment of the 'at-risk' population.
Researchers found that after adjusting for various confounders such as age, sex, body weight, smoking, hypnotics, and physical activity, subjects with persistent insomnia were 58 percent more likely to die during the study than subjects with no insomnia and that mortality was cardiovascular- rather than cancer-related. The study also determined that serum levels of C-reactive protein (CRP), an independent risk factor for mortality, was higher in subjects with persistent insomnia.
Investigators assessed the persistence of insomnia complaints in 1409 adult participants from the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD). The study commenced in 1972 with multiple follow-up surveys to 1996 and continuous mortality follow-up data to 2011 for a total of 38 years.
Using data from the baseline 1972-1973 survey and the 1990-1992 follow-up survey, the researchers found that serum CRP levels increased significantly only in the persistent-insomnia group. In those subjects where CRP data was available, persistent insomnia was associated with a 58 percent increased mortality risk (after adjustments for confounding factors). CRP levels are themselves associated with increased mortality, but even after adjusting for that factor, the mortality risk remained at 36 percent for subjects with persistent insomnia.
The study is published in the American Journal of Medicine.