Persistent Insomnia is Associated with Mortality Risk

Abstract

Background Insomnia has been associated with mortality risk, but whether this association is different in subjects with persistent versus intermittent insomnia is unclear. Additionally, the role of systemic inflammation in such an association is unknown. Methods We used data from a community-based cohort to determine whether persistent or intermittent insomnia, defined based on persistence of symptoms over a six-year period, were associated with death during the following 20-years of follow-up. We also determined whether changes in serum C-reactive protein (CRP) levels measured over two decades between study initiation and insomnia determination were different for the persistent, intermittent, and never insomnia groups. The results were adjusted for confounders such as age, sex, body mass index, smoking, physical activity, alcohol and sedatives. Results Of the 1409 adult participants, 249 (18%) had intermittent and 128 (9%) had persistent insomnia. During a 20-year follow-up period, 318 participants died (118 due to cardiopulmonary disease). In adjusted Cox proportional-hazards models, participants with persistent insomnia (adjusted Hazards Ratio [HR] 1.58, 95%CI: 1.02-2.45) but not intermittent insomnia (HR 1.22, 0.86-1.74), were more likely to die than participants without insomnia. Serum CRP levels were higher and increased at a steeper rate in subjects with persistent insomnia as compared with intermittent (p=0.04) or never (p=0.004) insomnia. Although CRP levels were themselves associated with increased mortality (adjHR: 1.36, 1.01-1.82, p=0.04), adjustment for CRP levels did not notably change the association between persistent insomnia and mortality. Conclusions In a population-based cohort, persistent, and not intermittent, insomnia was associated with increased risk for all-cause and cardiopulmonary mortality and was associated with a steeper increase in inflammation.