A good night's sleep may protect against heart disease and stroke
18 December 2019, 10:22
A good sleep pattern reduces the risk of heart disease and stroke by 34%, a study suggests.
The study, which is published in the European Heart Journal found that even if people had a high genetic risk of heart disease or stroke, this appeared to be offset to some extent by good sleep patterns.
The researchers studied the blood of nearly 400,000 people, looking for markers of high-risk heart problems and stroke.
The study, called Sleep patterns, genetic susceptibility, and incident cardiovascular disease: a prospective study of 385 292 UK biobank participants, examined samples from mainly middle-aged to older men and women.
The findings suggested even if people had a high genetic risk of heart disease or stroke, this appeared to be offset to some extent by good sleep patterns.
Led by Professor Lu Qi, director of Tulane University Obesity Research Centre at Tulane University in the US, they looked at genetic variations known as single nucleotide polymorphisms (SNPs) that were known to be linked to the development of heart disease and stroke.
Prof Qi and his colleagues also created a new, “healthy sleep score” by asking the participants whether they were a “morning” or an “evening” person, how long they slept for, and whether or not they suffered from insomnia, snoring or frequent, excessive daytime sleepiness.
The healthy sleep score ranged from 0 to 5, with 5 being the healthiest sleep pattern, representing a ‘morning” person, who slept between 7-8 hours a night, without insomnia, snoring or daytime sleepiness.
Compared with those with a sleep score of 0-1, participants with a score of 5 had a 35% reduced risk of cardiovascular disease, and a 34% reduced risk of both heart disease and stroke, according to the study.
Scientists analysed the SNPs from blood samples taken from 385,292 healthy participants in the UK Biobank project.
They used them to create a genetic risk score to determine whether the participants were at high, intermediate or low risk of cardiovascular problems.
Participants were followed for an average of 8.5 years, during which time there were 7,280 cases of heart disease or stroke.
Prof Qi said: "If the link between sleep and cardiovascular disease proves to be causal, 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 5.
"Among people with a healthy sleep score of 5, 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 5."
Researchers looked at the combined effect of sleep score and genetic susceptibility on cardiovascular disease.
They found that participants with both a high genetic risk and a poor sleep pattern had a more than 2.5-fold greater risk of heart disease and a 1.5-fold greater risk of stroke, compared with those with a low genetic risk and a healthy sleep pattern.
This meant that 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 with good sleepers with a low genetic risk.
According to the scientists, a healthy sleep pattern compensated slightly for a high genetic risk, with just over a two-fold increased risk for these people.
Prof 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."
But despite the good news, the study cannot show that better sleep actually causes a reduction in the risk of heart disease and stroke.