- Getting enough sleep cuts risks of dementia, heart disease, obesity and more
- But new University of Colorado, Boulder, research suggests that too much sleep may hurt the heart too
- People who got five or less hours of sleep were at a 52% higher risk of heart attack than average
- Heart attack risks were twice as high among those who slept more than 10 hours
- Getting between six and nine hours of sleep cut risks by 18%
Sleeping too much – or too little – raises the risk of a heart attack, warns major new research.
Less than five hours was linked to a 52 percent greater risk of heart attack, while those who slept more than 10 hours a night were at twice the risk.
Even for non-smokers who exercise and have no genetic predisposition to cardiovascular disease, skimping on sleep – or getting too much of it – increases the chances of a heart attack, according to the study of more than 460,000 British adults.
The findings, published in the Journal of the American College of Cardiology, also suggest that, for people at high genetic risk for heart attack, sleeping between six and nine hours each night can offset that risk.
On one hand, sleeping too much may increase overall inflammation, but sleeping too little could damage tissue and trigger habits like poor diet that contribute to heart attack risks, the University of Colorado, Boulder, researchers suggest.
People who don’t sleep enough, or sleep too much are both at elevated risks for heart attacks, a new study suggests – but getting between six and nine hours of rest cuts risks by 18%
Study senior author Dr Celine Vetter, Assistant Professor of Integrative Physiology at University of Colorado Boulder 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.’
For the study, Dr Vetter and colleagues at Manchester University and Massachusetts General Hospital analysed the genetic information, self-reported sleep habits and medical records of 461,000 UK participants age 40 to 69 who had never had a heart attack, then followed them for seven years.
Compared to those who slept six to nine hours per night, those who slept fewer than six hours were 20 percent more likely to have a heart attack during the study period.
Heart attacks were 34 percent more likely among those who slept more than nine hours a night.
When the researchers looked only at people with a genetic predisposition to heart disease, they found that sleeping between six and nine hours nightly cut their risk of having a heart attack by 18 percent.
‘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,’ said lead study author Iyas Daghlas, a medical student at Harvard University.
Previous studies suggested a link between sleep and heart health, but because they were observational – looking at different groups to see who develops disease – it was difficult to determine whether poor sleep causes heart problems or vice-versa.
For the new study, the researchers used the massive UK Biobank dataset and combined observational and genetic research to ask the question in a different way.
After taking into account 30 other factors – including body composition, physical activity, socio-economic status and mental health – they found that sleep duration, in and of itself, influenced heart attack risk independently of the other factors.
The farther people fell outside the six to nine hour per night sleep range, the more their risk increased.
For instance, people who slept five hours per night had a 52 percent higher risk of heart attack than those who slept seven to eight hours, while those who slept 10 hours nightly were twice as likely to have one.
The researchers then looked at the participants’ genetic profiles to determine whether those who were genetically predisposed to short sleep were more likely to have heart attacks; 27 genetic variants have been associated with short sleep.
The team discovered similar patterns, and found that genetically influenced short sleep duration was a risk factor for heart attack.
Dr Vetter said: ‘This gives us even more confidence that there is a causal relationship here – that it is sleep duration, not something else, influencing heart health.’
The study did not explore the mechanism by which short or long sleep may boost heart attack risk, but previous studies have pointed to a few explanations.
Sleeping too little can impact the lining of the arteries, or endothelium, impact bone marrow development of inflammatory cells, but also lead to poor dietary choices and ill-timed eating – which can in turn impact weight and, also, heart health.
The researchers said that too much sleep may also boost inflammation in the body, which is also associated with cardiovascular disease.
They hope their findings will increase awareness about sleep’s heart-health benefits.
Dr Vetter added: ‘Just as working out and eating healthy can reduce your risk of heart disease, sleep can too.’