Good sleep patterns can help reduce your risk of heart disease or stroke, even if you're at high genetic risk, new research shows.
In fact, the study of several hundred thousand people found that having a "healthy sleep score" of five (on a scale of zero to five) appeared to reduce a person's odds for heart disease and stroke by about a third.
Maintaining sleep quality
So, if better sleep does result in a healthier heart, "then more than a tenth of all heart disease and strokes would not have occurred if all the participants had a healthy sleep score of five," said study lead author Dr Lu Qi. He directs the Obesity Research Center at Tulane University in New Orleans.
Put another way, Among people with a healthy sleep score of five, there were nearly seven fewer cases of cardiovascular disease per 1 000 people per year compared to those with a sleep score of less than five," Qi said.
His team published their findings in the European Heart Journal.
One expert unconnected to the study said maintaining sleep quality should be on every heart patient's to-do list.
"This study suggests that if we can manipulate our sleep in a healthy fashion, then we may be able to limit the effects of other cardiovascular risks, such as our genetics," said Dr Thomas Kilkenny, director of sleep medicine at Staten Island University Hospital in New York City.
In their research, Qi and his colleagues analysed blood samples from more than 385 000 healthy people in the United Kingdom. They looked for specific genetic variations called SNPs (single nucleotide polymorphisms) that have long been associated with the development of heart disease and stroke.
A 'healthy sleep score'
Based on these analyses, the team created a genetic score of a high, intermediate or low risk of heart disease and stroke among the participants.
The researchers also gave each participant a "healthy sleep score" based on whether they were a morning or evening person, how long they slept each night, and whether they had insomnia, snoring or frequent excessive daytime sleepiness.
The sleep score ranged from zero to five, with five being the healthiest, which included being a morning person, sleeping seven to eight hours a night, and not having insomnia, snoring or daytime sleepiness.
During an average follow-up of 8.5 years, there were nearly 7 300 cases of heart disease or stroke among the study participants.
Compared to those with a sleep score of zero to one, participants with a score of five had a 35% lower risk of heart disease, and a 34% lower risk of both heart disease and stroke, the study found.
When they examined the combined impact of sleep score and genetic susceptibility on heart disease, the researchers found that participants with both a high genetic risk and a poor sleep score had a more than 2.5-fold greater risk of heart disease and a 1.5-fold greater risk of stroke, compared to people with a low genetic risk and a healthy sleep pattern.
A high genetic risk
This means there were 11 more cases of heart disease and five more cases of stroke per 1 000 people a year among poor sleepers with a high genetic risk compared to good sleepers with a low genetic risk, the researchers said.
However, "We found that a high genetic risk could be partly offset by a healthy sleep pattern," Qi said in a journal news release.
And on the other hand, "people with a low genetic risk could lose this inherent protection if they had a poor sleep pattern," he said.
People with a high genetic risk but healthy sleep had a 2.1-fold higher risk of heart disease and a 1.3-fold higher risk of stroke than those with a low genetic risk and a good sleep score. People with a low genetic risk, but a low sleep score had 1.7-fold greater risk of heart disease and a 1.6-fold greater risk of stroke.
Qi stressed, "As with other findings from observational studies, our results indicate an association, not a causal relation." But he believes the study should help spur new research into a link between heart health and sleep.
Just how much sleep is enough?
Dr Guy Mintz directs cardiovascular health at Northwell Health's Sandra Atlas Bass Heart Hospital in Manhasset, New York. He wasn't part of the research but said he wasn't surprised by the new findings.
"It is well-known that abnormal sleep patterns are associated with an increased risk for cardiovascular events including heart attack and stroke," Mintz said. "Understanding that proper sleep plays a role in cardiovascular 'event' reduction is one key risk factor that may increase event reduction further."
Just how much sleep is enough? According to Mintz, "It has been proven six to nine hours of sleep is heart-healthy. And the benefit seen in this study [from good sleep] is as good as some statin therapies."
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