Studies have shown that if you’re a long-term couch potato, your heart health may be at risk. The same goes for people who eat too much fast food.

Now, a new study has found that if you’re not sleeping enough, or sleeping more than you should, you may face the risk of a heart attack. 

More isn’t always better

A study by the University of Colorado Boulder on nearly half a million people found that even if you’re a non-smoker and you have no genetic predisposition to cardiovascular disease, the amount of sleep you get can have an impact your heart attack risk. The study, published in the Journal of American College of Cardiology, found that sleeping between six and nine hours a night could offset the risk. 

In the study, authors looked at the genetic information, self-reported habits and the medical records of 461 000 UK Biobank participants between the ages of 40 and 69 who had never had a heart attack and followed them over a period of seven years.

In comparison to participants who slept six to nine hours a night, participants who got fewer than six hours of sleep were 20% more likely to have a heart attack during the period of study. Surprisingly, participants who slept for more than nine hours a night were 34% more likely to have a heart attack. Researchers also looked at people with a genetic predisposition to heart disease and found that sleeping between six to nine hours a night cut their risk of having a heart attack by 18%. 

A healthy amount

Celine Vetter, assistant professor of Integrative Physiology and senior author of the study said, “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.” Lead author Iyas Daghlas added, “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.”

Sleep and heart health were always associated in previous research, but due to the fact that most studies were observational – looking at different groups to see who would develop disease – it was more difficult to determine whether it was poor sleep which caused heart problems or whether heart problems were the result of poor sleep. 

Contributing factors

In the new study, researchers used the UK Biobank dataset and combined observational as well as genetic research in order to ask the questions in a different way. A total of 30 other factors were looked at and included: 

• Body composition
• Physical activity
• Socioeconomic status
• Mental health

It was found that sleep duration influenced heart attack risk independently of these factors.

People who fell out of the six to nine hour range had a more increased risk of a heart attack. People who slept five hours per night had a 52% higher risk of a heart attack than those who slept seven to eight hours. Participants who slept 10 hours a night were twice as likely to have a heart attack. Researchers found that genetically influenced short sleep duration was also a risk factor for a heart attack.

The study did not look into the mechanisms by which sleep duration may boost a heart attack risk.

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Deeanne Daniels