, according to a large cohort study of adults in China. A greater number of insomnia symptoms is associated with increased risk, and this relationship is more evident in younger adults and in adults without hypertension at baseline, researchers reported Nov. 6 in Neurology.
Karen Winton/iStockphoto
“These results suggest that, if we can target people who are having trouble sleeping with behavioral therapies, it’s possible that we could reduce the number of cases of stroke, heart attack, and other diseases later down the line,” study author Liming Li, MD, professor of epidemiology at Peking University, Beijing, said in a news release.
To clarify the relationships between individual insomnia symptoms, cardiocerebral vascular diseases, and potential effect modifiers, Dr. Li and colleagues analyzed data from the China Kadoorie Biobank Study. For this study, more than 500,000 adults in China aged 30-79 years completed a baseline survey during 2004-2008. The present analysis included data from 487,200 participants who did not have a history of stroke, coronary heart disease, or cancer at baseline.
For the baseline survey, participants answered questions about whether specific insomnia symptoms occurred at least 3 days per week during the past month. The symptoms included difficulty initiating or maintaining sleep (that is, sleep onset latency of 30 minutes or more after going to bed or waking up in the middle of the night); waking too early and being unable to fall back asleep; and trouble functioning during the day because of bad sleep.
The researchers assessed the incidence of cardiocerebral vascular diseases through 2016 by examining disease registries, national health insurance claims databases, and local records. Investigators identified participants with any cardiocerebral vascular disease and assessed the incidence of ischemic heart disease, acute myocardial infarction, hemorrhagic stroke, and ischemic stroke. The researchers followed each participant until the diagnosis of a cardiocerebral vascular disease outcome, death from any cause, loss to follow-up, or Dec. 31, 2016. The researchers used Cox proportional hazard models to estimate hazard ratios for the association between each insomnia symptom and cardiocerebral vascular disease outcomes. They adjusted the models for established and potential confounding factors, including age, income, smoking status, diet, and physical activity.
More than 16% had any insomnia symptom
Of the 487,200 participants, 11.3% had difficulty initiating or maintaining sleep, 10.4% had early morning awakening, and 2.2% had daytime dysfunction attributed to poor sleep. Compared with participants without insomnia symptoms, participants with insomnia symptoms tended to be older and were more likely to be female, not married, and from a rural area. In addition, those with insomnia symptoms were more likely have depression or anxiety symptoms, lower education level, lower household income, and lower body mass index. They also were more likely to have a history of diabetes mellitus. During a median follow-up of 9.6 years, 130,032 cases of cardiocerebral vascular disease occurred, including 40,348 cases of ischemic heart disease and 45,316 cases of stroke.