Getting a good sleep routine could cut your chances of heart disease and stroke – even if you’re genetically at-risk, researchers claim.
Scientists calculated a ‘sleep score’ for 385,000 people, based on factors such as how many hours they slept for each night.
All of their DNA was then screened to allow experts to compare sleep against their genetic susceptibility of cardiovascular disease (CVD), which includes heart disease and stroke.
Results revealed regularly getting between seven and eight hours a night lowered the risk of battling either of the killer ailments.
And the risk was also slashed for participants deemed at-risk due to their genetics, according to the team at Tulane University in New Orleans.
A healthy sleeping pattern lowered the risk of heart disease and stroke, even among people who are genetically vulnerable to the potentially fatal problems, scientists say
Lead author Professor Lu Qi said: ‘We found that a high genetic risk could be partly offset by a healthy sleep pattern.
‘In addition, we found that people with a low genetic risk could lose this inherent protection if they had a poor sleep pattern.’
Professor Lu Qi and his colleagues created a ‘healthy sleep score’ from zero to five, with five being the healthiest sleep pattern.
This would represent a ‘morning person’, who slept between seven and eight hours a night, without insomnia, snoring or daytime sleepiness.
The genetic makeup of 385,292 healthy participants from the UK was analysed using blood samples.
They were looking for variations known as single nucleotide polymorphisms, already known to be linked to the development of CVD.
The researchers followed the participants for an average of 8.5 years, during which time there were 7,280 cases of CVD – 4,667 cases of heart disease and 2,650 strokes.
Participants who saw the greatest protection were those with low genetic risk and a good sleeping pattern.
Compared to them, poor sleepers who were genetically at-risk were 2.5 times more likely to be struck down with heart disease.
They were also at a 1.5-fold higher risk of stroke in the follow-up period, according to the results.
This meant there were an extra 11 more cases of heart disease and five more strokes per 1,000 people each year.
However, these effects were reversed a little if the genetically at-risk participants had a high sleeping score.
Results showed they were only 2.1 times more likely to develop heart disease, and had a 1.3-fold higher risk of stroke.
Volunteers with a low genetic risk but an unhealthy sleep pattern had 1.7-fold greater risk of heart disease and a 1.6-fold greater risk of stroke.
Looking at sleep alone, there was a 35 per cent lower risk of CVD between those with the worst and best sleep patterns.
That means nearly 10 per cent of cardiovascular events – either heart disease or stroke – in the participants could be attributed to poor sleep pattern, Professor Qi said.
WHY IS SLEEP LINKED TO HEART PROBLEMS?
The amount of time a person sleeps has been linked to their risk of cardiovascular disease and premature death. However, it is currently unclear if the lack of sleep is what directly causes the life-threatening problems, whether they are just genetically linked, or other factors are to blame.
Adults who sleep less than seven hours each night are more likely to say they have had health problems, including heart attack, asthma, and depression, according to the CDC. Some of these health problems raise the risk for heart disease, heart attack, and stroke.
Experts at the Karolinska Institutet in Sweden found evidence sleep and heart diseases, such as CAD, heart failure, ischemic stroke and atrial fibrillation, are genetically linked.
They analysed data from 1.3million people and found people at genetic risk of insomnia were found to have an increased risk of heart attacks by 13 per cent, of heart failure by 16 per cent, and of strokes by seven per cent.
Another study found that sleeping too much is a risk to health. People who slept longer than eight hours had a higher risk of dying or developing diseases of the heart or blood vessels in the brain compared to those who slept for between six and eight hours.
The researchers at McMaster and Peking Union Medical College, Chinese Academy of Medical Sciences, China, examined data on 116,000 people aged between 35 and 70 from 21 different countries.
Figures from the Royal Society for Public Health estimate the average person sleeps for 6.8 hours a night, but the NHS recommends people get eight hours.
Lack of sleep shortens your life expectancy, according to the NHS, and has previously been linked to a greater risk of cancer.
More than 40million people suffer from long-term sleep disorders in the US, data from the CDC shows. While it is estimated there are 1.5million patients in the UK.
However, the study did not prove poor sleep causes CVD. It just adds to the array of evidence linking the two.
Good quality sleep is known to play a vital role in heart health, but the exact underlying reasons are not currently clear.
Adults who sleep less than seven hours a day are more likely to complain of having high blood pressure, type 2 diabetes or obesity, according to the CDC. These are each risk factors for CVD.
Independent academics said the study confirmed previous findings that disturbed sleep patterns are linked with CVD. But it cannot prove the risk of CVD was not attributable to other factors at play, such as obesity.
Professor Stephen MacMahon, from The George Institute for Global Health, said: ‘It’s the chicken or the egg dilemma.
‘In previous studies it was difficult to disentangle risks associated with poor sleep from risks associated with other causes of cardiovascular disease, and this is also the case here.
‘People with poor sleep quality were more likely to have diabetes, hypertension and a range of other risk factors including obesity, which reduces the quality of sleep through snoring and sleep apnoea as well as increasing cardiovascular disease risks.’
Professor Jeremy Pearson FMedSci, associate medical director, British Heart Foundation (BHF), said sleep patterns often reflect other aspects of health which are tied to CVD risk.
He said: ‘The novel assessment of sleep behaviour did not pinpoint any one behaviour type as being more strongly associated with cardiovascular risk.’
Cardiovascular disease (CVD) is a general term for conditions affecting the heart or blood vessels.
Heart disease strikes eight million people across the UK, the British Heart Foundation says. It kills 40,000 people under the age 75 every year.
There are more than 100,000 strokes in the UK each year – around one stroke every five minutes, according to Stroke Association.
About 647,000 Americans die from heart disease each year and 140,000 people die from stroke, the CDC say.
The study relied only on volunteers reporting their own sleep patterns and did not account for other problems like restless legs syndrome.
The findings were published in the European Heart Journal.