Too much or too little sleep increases heart attack risk, study finds

BOULDER, Colo. — Everyone knows getting enough sleep each night is an important part of maintaining a healthy lifestyle, but people most often associate sleep with alertness, well being, or mental clarity, not their cardiovascular health. Now, a new study conducted at the University of Colorado finds that sleep duration has a profound effect on one’s risk of suffering a heart attack.

According to researchers, not getting enough sleep, or getting too much, increases risk of heart attack. This holds true even for those who don’t smoke, exercise, and have no genetic predisposition to cardiovascular disease.

Interestingly, the study also indicated that individuals with a high genetic risk of suffering a heart attack can offset that risk by regularly getting between six and nine hours of sleep per night.

“This provides some of the strongest proof yet that sleep duration is a key factor when it comes to heart health, and this holds true for everyone,” comments Celine Vetter, senior author and assistant professor of Integrative Physiology, in a media release.

Researchers analyzed the genetic information, sleeping habits, and medical records of 461,000 participants between the ages of 40 and 69 who had never had a heart attack. Then, each participant was tracked for seven years.

Compared to participants who slept six to nine hours per night, those who slept fewer than six hours each night were 20% more likely to have a heart attack during the duration of the study. Conversely, those who slept more than nine hours per night were 34% more likely to suffer a heart attack.

When the research team only looked at people with an elevated genetic risk of a heart attack, they discovered that sleeping between six to nine hours per night cut that risk by 18%.

“It’s kind of a hopeful message, that regardless of what your inherited risk for heart attack is, sleeping a healthy amount may cut that risk just like eating a healthy diet, not smoking, and other lifestyle approaches can,” comments lead author Iyas Daghlas.

It’s long been suggested that sleep is linked to heart health, but previous research on the topic was inconclusive, mainly because the studies conducted were observational and failed to distinguish if sleep duration was causing heart problems or vice versa. Furthermore, multiple factors can potentially influence both sleep duration and heart health, which has made it even harder to establish a definitive cause and effect relationship.

So, for this study the research team took a different approach; combining a large dataset with both observational and genetic research.

After accounting for 30 other factors that may affect heart attack risk, including body composition, physical activity, socioeconomic status, and mental health, researchers found that sleep duration alone can influence heart attack risk regardless of these other factors.

It is worth noting that the farther participants fell out of the six to nine hour sleep range, the higher their risk of heart attack became. For example, people who slept five hours per night had a 52% higher chance of suffering a heart attack than those who slept seven to eight hours per night.

The study’s authors also analyzed each participant’s genetic profile in order to investigate if individuals with a genetic predisposition to sleep less were more likely to suffer a heart attack. They found that genetically-influenced sleep duration was indeed a risk factor for heart attacks.

“This gives us even more confidence that there is a causal relationship here – that it is sleep duration, not something else, influencing heart health,” Vetter explains.

The research team hope that their work helps raise awareness about sleep’s connection to heart health.

“Just as working out and eating healthy can reduce your risk of heart disease, sleep can too,” Vetter concludes.

The study is published in the Journal of the American College of Cardiology.