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Sleeping less than six hours a night can increase your risk of heart attack by up to 35%

Sleeping less than six hours a night may increase your risk of heart attack or stroke, a new study warns.

Researchers say getting less than six hours of shut-eye increased the risk of cardiovascular disease by up to 35 percent compared to those who slept between seven and eight hours a night.

Lack of sleep raises the risk of atherosclerosis, which is a build-up of plaque in the body’s arteries that causes them to narrow and harden.

The team, led by the Spanish National Center for Cardiovascular Research (CNIC) in Madrid, says the findings show that changing patterns of sleep could be faster and cheaper than treating heart disease with certain drugs.

Getting less than six hours of sleep increased the risk of cardiovascular disease by up to 35 percent compared to those who slept between seven and eight hours a night, a new study found (file image)

For the study, published in the Journal of the American College of Cardiology, the team looked at nearly 4,000 bank employees in Spain. 

The participants were 46 years old on average with no known history of heart disease from the CNIC-Santander PESA study, which looks at how cardiovascular disease advances.

To measure sleep, they wore an actigraph – a watch-like device that continuously measures movement and light exposure – over seven days.

Researchers split the participants into four groups: less than six hours of sleep, six to seven hours of sleep, seven to eight hours of sleep, and eight hours or more of sleep.

The adults were also given 3-D heart ultrasounds and CT scans to look for evidence of cardiovascular disease. 

Lastly, the team looked at quality of sleep, which was measured by how often someone woke up in the middle of the night and how often they moved in their sleep.

Participants who slept less than six hours every night were 27 percent more likely to have atherosclerosis than those who slept seven to eight hours every night.

Additionally, participants with poor quality of sleep were 34 percent more likely to  have the disease that participants with good quality of sleep. 

There was also an association between those who slept more than eight hours a night and atherosclerosis risk.

Researchers found that particularly women who slept that long every night were more likely to have it. 

‘It is important to realize that shorter sleep duration that is of good quality can overcome the detrimental effects of the shorter length,’ said Dr Valentin Fuster, the editor-in-chief of the Journal of the American College of Cardiology.   

The team also looked at other factors that affected sleep quality and found high alcohol and caffeine consumption among those with poor quality.  

‘Many people think alcohol is a good inducer of sleep, but there’s a rebound effect,’ said senior study author Dr José Ordovás, a researcher at CNIC and a senior scientist at Tufts University. 

‘If you drink alcohol, you may wake up after a short period of sleep and have a hard time getting back to sleep. And if you do get back to sleep, it’s often a poor-quality sleep.’

Several studies have said drinking coffee can be good for the heart, but Dr Ordovás says those positive effects are only present if someone metabolizes coffee quickly.

‘Depending on your genetics, if you metabolize coffee faster, it won’t affect your sleep. But if you metabolize it slowly, caffeine can affect your sleep and increase the odds of cardiovascular disease,’ he said. 

Dr Ordovás says improving sleep is faster and easier than current pharmaceutical approaches to cardiovascular disease. 

‘This study emphasizes we have to include sleep as one of the weapons we use to fight heart disease – a factor we are compromising every day,’ he said. 

‘This is the first study to show that objectively measured sleep is independently associated with atherosclerosis throughout the body, not just in the heart.’  

In an editorial, Dr Daniel Gottlieb, an associate professor of medicine at Harvard Medical School and Dr Deepak L Bhatt, a professor of cardiovascular medicine at Harvard Medical School, say more research is needed to confirm if changing sleep quality and quantity can improve heart health.

‘The potentially enormous impact of sleep deprivation and disruption on population health, reinforced by the present study, is ample justification for such trials, which are needed to place sleep with confidence alongside diet and exercise as a key pillar of a healthy lifestyle,’ they wrote. 


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