Zheng B, et al. Neurology. 2019;doi:10.1212/WNL.0000000000008581.

November 6, 2019

Symptoms of insomnia, specifically difficulties in falling and staying asleep, early morning awakening and daytime dysfunction, were independent risk factors for the incidence of CVD, especially in young adults or those without hypertension, according to a study published 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,” Liming Li, MD, of the department of epidemiology and biostatistics at the Peking University Health Science Center School of Public Health in Beijing and the Chinese Academy of Medical Sciences in Beijing, said in a press release.

Data from China Kadoorie Biobank

Bang Zheng, MD, MSc, of the department of epidemiology and biostatistics at Peking University Health Science Center School of Public Health and of the neuroepidemiology and aging research unit at Imperial College London School of Public Health, and colleagues analyzed data from 487,200 patients (mean age, 51 years; 199,241 men) from the China Kadoorie Biobank Study without a history of CHD, stroke or cancer.

A baseline survey was conducted to collect information on specific insomnia symptoms for at least 3 days per week in the past month. Patients with one or more of the following were considered to have insomnia symptoms: difficulties in initiating or maintaining sleep, early morning awakening or daytime dysfunction.

The main outcomes of interest were incidences of CVD, acute MI, ischemic heart disease, stroke, hemorrhagic stroke and ischemic stroke.

There were 130,032 cases of total CVD incidence during a median follow-up of 9.6 years.

An increased risk for total CVD was seen with all three symptoms of insomnia, specifically difficulties in maintaining or initiating sleep (HR = 1.09; 95% CI, 1.07-1.11), early morning awakening (HR = 1.07; 95% CI, 1.05-1.09) and daytime dysfunction (HR = 1.13; 95% CI, 1.09-1.18).

Patients with any insomnia symptoms had an increased risk for ischemic heart disease (HR = 1.13; 95% CI, 1.09-1.17). Symptoms of insomnia were also associated with a slightly increased risk for the incidence of total stroke (HR range = 1.05 to 1.08; P < .05) and ischemic stroke (HR range = 1.06 to 1.09; P < .05). This link was not seen for the incidence of hemorrhagic stroke (P > .05).

Compared with patients without symptoms, those with all three symptoms had an 18% increased risk for CVD, 22% increased risk for ischemic heart disease and 10% higher risk for ischemic stroke.

Strong associations

The links between the three symptoms of insomnia and the incidence for CVD were stronger in younger patients (P for interaction < .05) and those without baseline hypertension (P for interaction < .05).

“Future clinical trials or community-based intervention studies should be conducted to test whether lifestyle or sleep hygiene interventions for insomnia symptoms can reduce subsequent CVD risks,” Zheng and colleagues wrote. – by Darlene Dobkowski

Disclosures: The authors report no relevant financial disclosures.

Editor’s Note: This article was updated on Nov. 25, 2019 to restate statistics relating to the risk for total stroke and ischemic stroke. The Editors regret the errors.

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Insomnia and short sleep have been recently identified as risk factors for CV events. However, this study is the largest to date, as it includes nearly half a million participants, adding confidence and confirmation to previous studies. This study also is the first to evaluate younger adults, further extending our understanding of the impact of insomnia. Expanding to younger individuals with no existing CVD further underscores the importance of insomnia and sleep time.

The study has a limitation, as it relied on self-reports and was not able to rule out the existence of other sleep disorders such as sleep apnea.

The findings have significant implications to public health and clinical practice. Inquiring on insomnia or short sleep are not part of standard preventive health care at this time. Whether intervening to increase sleep time decreases CV risk is not known yet, however.

It is important to perform physiological studies to determine whether treating insomnia or expanding sleep results in decreased markers of CVD.

Rami Khayat, MD
Professor
Department of Psychiatry and Human Behavior
Division of Pulmonary and Critical Care Medicine
University of California, Irvine School of Medicine
Medical Director, University of California, Irvine Sleep Disorders Center
Director, Pulmonary and Critical Care Fellowship Program
Disclosures: Khayat reports no relevant financial disclosures.