New research has found a link between insomnia and an increased risk of heart attack and stroke.

“Sleep is important for biological recovery and takes around a third of our lifetime, but in modern society more and more people complain of insomnia,” said first author Qiao He, a graduate student at China Medical University in Shenyang, China. “For example, it is reported that approximately one-third of the general population in Germany has suffered from insomnia symptoms.”

“Researchers have found associations between insomnia and poor health outcomes,” she continued. “But the links between insomnia and heart disease or stroke have been inconsistent.”

The meta-analysis assessed the association between insomnia symptoms and incidence or death from cardiovascular disease (acute myocardial infarction, coronary heart disease, heart failure), stroke, or a combination of events.

Insomnia symptoms included difficulty initiating sleep, difficulty maintaining sleep, early morning awakening, and non-restorative sleep.

The researchers analyzed 15 prospective cohort studies with a total of 160,867 participants. During a median follow-up of three to 29.6 years, there were 11,702 adverse events, they discovered.

They also discovered there were significant associations between difficulty initiating sleep, difficulty maintaining sleep, and non-restorative sleep and the risk of heart disease and stroke, with increased relative risks of 1.27, 1.11, and 1.18, respectively, compared to those not experiencing these insomnia symptoms.

There was no association between early morning awakening and adverse events, according to the study’s findings.

“We found that difficulty initiating sleep, difficulty maintaining sleep, or non-restorative sleep were associated with 27 percent, 11 percent and 18 percent higher risks of cardiovascular and stroke events, respectively,” she said.

“The underlying mechanisms for these links are not completely understood,” she said. “Previous studies have shown that insomnia may change metabolism and endocrine function, increase sympathetic activation, raise blood pressure, and elevate levels of pro-inflammatory and inflammatory cytokines — all of which are risk factors for cardiovascular disease and stroke.”

Women with insomnia symptoms had a slightly higher risk of cardiovascular and stroke events than men, especially for non-restorative sleep, but the difference between sexes did not reach statistical significance, she noted.

“We cannot conclude that insomnia is more dangerous for women, given the limitations of meta-analyses and the lack of a statistically significant difference between sexes,” said He. “However, we do know that women are more prone to insomnia because of differences in genetics, sex hormones, stress, and reaction to stress. It may therefore be prudent to pay more attention to women’s sleep health.”

“Sleep disorders are common in the general population and sleep health should be included in clinical risk assessment,” she said. “Health education is needed to increase public awareness of insomnia symptoms and the potential risks, so that people with sleep problems are encouraged to seek help.”

The study was published in the European Journal of Preventive Cardiology.

Source: European Society of Cardiology

Insomnia Tied to Greater Risk of Heart Attack, Stroke