Signs of insomnia were tied to higher rates of incident cerebrovascular and cardiovascular disease, especially in younger and nonhypertensive adults, an observational study of a half million people in China showed.
Three insomnia symptoms — trouble falling or staying asleep, waking up too early, and daytime dysfunction due to poor sleep — were linked to higher rates of ischemic heart disease and stroke over 10 years, according to Liming Li, MD, of Peking University in Beijing, and coauthors.
After adjusting for potential confounders including age, tea and alcohol consumption, physical activity, sleep aid use, snoring frequency, depression, and anxiety, each insomnia symptom was tied to significantly elevated cerebrovascular and cardiovascular disease risk:
- 9% increased risk for difficulty initiating or maintaining sleep
- 7% increased risk for early morning waking and not being able to get back to sleep
- 13% increased risk for daytime dysfunction because of bad sleep
Each insomnia symptom upped the risk of cardiovascular and cerebrovascular disease significantly, they reported in Neurology.
“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,” Li said in a statement.
“The link between insomnia symptoms and these diseases was even stronger in younger adults and people who did not have high blood pressure at the start of the study, so future research should look especially at early detection and interventions aimed at these groups,” he added.
This research “supports and expands emerging knowledge about the contribution of disturbed sleep for cardiovascular and, more specifically, cerebrovascular diseases,” noted Dirk Hermann, MD, of the University Hospital Essen in Germany, who was not involved with the study.
“By a number of factors, which include but are not limited to sleep apnea, sympathetic activation, development of arterial hypertension, and development of glucose intolerance, disturbed sleep contributes to cardiovascular and cerebrovascular events,” Hermann told MedPage Today.
“Sleep disturbances are mostly easy to recognize,” he added. “As neurologists, we too often overlook them on stroke units and ICU wards.”
Systematic reviews and meta-analyses have pointed to strong ties between baseline insomnia and risks of myocardial infarction (MI) and stroke. A recent meta-analysis showed that more than 50% of patients with transient ischemic attack or stroke had sleep-disordered breathing. A longitudinal study also reported that young adults with insomnia had an eight-fold higher risk for stroke than those of the same age without sleep problems.
In this analysis, Li and colleagues analyzed data from the China Kadoorie Biobank, a prospective cohort study of adults from 10 areas in China who completed a baseline survey from 2004 to 2008.
The study looked at data from 487,200 participants (199,241 men and 287,959 women) with an average age of 51. It excluded people with a history of stroke, coronary heart disease, or cancer.
At baseline, participants reported whether they had any of three insomnia symptoms at least 3 days a week in the past month: difficulty initiating or maintaining sleep (DIMS), early morning waking and not being able to get back to sleep (EMA), and daytime dysfunction because of bad sleep (DDF). Overall, 16.4% of participants reported any insomnia symptoms: 11.3% of participants reported DIMS, 10.4% reported EMA, and 2.2% reported DDF.
The researchers determined cerebrovascular and cardiovascular incidence through disease registries, national health insurance claim databases, and local residential records. Over a median of 9.6 years of follow-up, 130,032 incident cases of cerebrovascular and cardiovascular disease were documented, including 40,348 cases of ischemic heart disease and 45,316 stroke cases.
People with DIMS, EMA, or DDF had greater risk of ischemic heart disease than people without corresponding insomnia symptoms, but only DIMS was associated with a higher risk of acute MI (HR 1.09, P<0.05). Each insomnia symptom was associated with increased risks of ischemic stroke (HRs of 1.06 to 1.09, P<0.05) but not hemorrhagic stroke.
People who had all three insomnia symptoms had an 18% higher risk of cerebrovascular or cardiovascular disease, a 22% higher risk of ischemic heart disease, and a 10% higher risk of ischemic stroke compared with non-symptomatic adults.
Associations between insomnia symptoms and cerebrovascular and cardiovascular disease consistently were stronger in people under age 50 or without baseline hypertension (P for interaction <0.05).
The study had several limitations, the researchers noted. It did not include information about non-restorative sleep. Insomnia symptoms were self-reported and were assessed only at baseline. The analysis could not show casual relationships, only an association between insomnia symptoms and incident stroke and heart disease, Li added.
Last Updated November 06, 2019
The study was supported in part by the National Key Research and Development Program of China, the Chinese Ministry of Science and Technology, and the National Natural Science Foundation of China.
The researchers reported no relevant disclosures.