Men's silhouette against the background of the full blood moonShare on Pinterest
New research found an association between insomnia and a higher risk of cardiovascular events. VeroRo39/Getty Images
  • A new meta-analysis of 21 studies involving more than 2 million people analyzes how insomnia impacts heart disease risk.
  • The researchers compared data between healthy individuals without insomnia and people with insomnia.
  • The results show that people with insomnia had a higher risk of cardiovascular events, including myocardial infarctions and cardiovascular death.
  • Additionally, all-cause mortality related to insomnia showed a 14% higher risk than healthy individuals.

Most people have had trouble sleeping at some point, whether due to stress or medical conditions.

When someone regularly has difficulty falling asleep or getting a full night’s rest, this is called insomnia.

According to the National Library of Medicine, insomnia affects more than 30% of adults worldwide. People with insomnia often experience a higher risk for other health issues such as diabetes, kidney disease, and gastrointestinal disorders.

Some past research points to insomnia increasing the risk of cardiovascular disease (CVD), while other studies indicate no connection.

These contradictory findings were the impetus for a new meta-analysis that sought to determine whether insomnia impacts the heart and to what degree.

The study appears in PLoS One.

While some studies analyze possible associations between insomnia and heart conditions, the present study’s authors noted that the studies are contradictory.

The researchers said older studies tended to show a connection between insomnia and heart issues, while newer studies showed “no significant association.”

Additionally, they note, “data incorporating recent clinical studies evaluating these outcomes is scarce.”

With this in mind, they scoured medical databases to compile a comprehensive meta-analysis to see if data from the past 20 years may point toward a link between insomnia and cardiovascular conditions.

The researchers used data from 21 studies that included approximately 389,000 individuals with insomnia and more than 2 million healthy individuals.

The studies following these people tracked them anywhere from 3 to 20 years, and the participants had to be at least 18 years of age or older for inclusion.

Other criteria for inclusion involved:

  • outcomes for cardiovascular mortality
  • myocardial infarction incidents
  • cardiovascular disease incidents
  • all-cause mortality related to insomnia

The researchers did not include studies that involved minors or animals or had no controls.

The average age of the study participants was 59.4 years for the insomnia group and 58.6 years for the healthy group.

After analyzing the data and comparing healthy individuals to people with insomnia, the researchers learned that there was a correlation between insomnia and a number of adverse health events.

The authors said that people with insomnia had a much higher risk of cardiovascular death. People with insomnia had a 53% increased risk of having a heart disease-related death compared to healthy individuals.

Insomnia was also connected to a significant increase in heart attack risk. People with insomnia had a 48% higher risk for heart attacks than healthy people.

Another significant finding was that people with insomnia had a 31% higher chance of developing any type of cardiovascular disease.

Finally, the authors learned that people with insomnia had a 14% higher chance of all-cause mortality compared to healthy individuals.

When looking at data available on people from studies that followed participants for 10 to 20 years, the researchers saw that dying from any cause was much higher for people with insomnia. This suggests that insomnia can impact people down the road rather than just being problematic in the short term.

The researchers speculated on why insomnia may impact the cardiovascular system and mentioned that the autonomic nervous system being unmodulated and systemic inflammation may be contributing factors.

Dr. Cheng-Han Chen, interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, California, spoke with Medical News Today about the study. Dr. Chen explained how insomnia may impact heart health.

“Insomnia likely negatively impacts heart health through a combination of mechanisms, such as increasing sympathetic nervous system activity, dysregulating autonomic nervous system activity, and increasing systemic inflammation,” commented Dr. Chen.

“Insomnia is also frequently concurrent with obstructive sleep apnea, a known risk factor for cardiovascular disease,” Dr. Chen continued. “Finally, insomnia can promote hypertension, another risk factor for cardiovascular disease.”

While Dr. Chen found the study helpful overall, he noted a study limitation.

“It is limited by significant heterogeneity in not only insomnia definition across the studies but also in the clinical and methodological variability between the studies. In addition, the observational studies from which the meta-analysis was based upon are inherently limited by inability to show a causal relationship; i.e. whether insomnia results in cardiovascular disease, or whether underlying cardiovascular disease results in more insomnia.”

— Dr. Cheng-Han Chen, cardiologist

Dr. Nicole Weinberg, board-certified cardiologist at Providence Saint John’s Health Center in Santa Monica, California, also shared her thoughts on the study with MNT.

“Many times people have undiagnosed sleep disorders, such as obstructive sleep apnea, that can be very dangerous to the heart,” said Dr. Weinberg.

“Diseases such as obstructive sleep apnea can cause hypertension, weight gain, and pulmonary hypertension,” noted Dr. Weinberg. “These things can lead to increased morbidity and mortality as it relates to one’s cardiovascular health.”

When asked about the study’s strengths or weaknesses, Dr. Weinberg highlighted something the authors mentioned.

“This study acknowledges that it would be interesting to control for variables, such as obstructive sleep apnea, to be able to determine if there are other aspects of insomnia that are detrimental to cardiovascular disease,” Dr. Weinberg said.

Dr. Chen had a few recommendations for people looking to improve their sleep quality.

“Patients with insomnia can try to adopt healthy sleep habits such as keeping their bedroom cool, dark and quiet, avoiding caffeine and alcohol, going to sleep around the same time each day, getting regular exercise during the day, and avoiding naps in the afternoon.”

This is in line with recommendations from the National Institute of Health. The organization also mentions learning how to manage stress as a way to improve sleep.

Dr. Weinberg noted that “workups for sleep disorders are becoming more common and covered by insurance.”

As a result, the doctor notes that the medical profession is in a place to better identify sleep disorders.

“Hopefully we will be able to treat them earlier and be able to circumvent the detrimental effects associated with these disorders,” said Dr. Weinberg.