Share on Pinterest- A new study found that older adults who maintained good sleep quality over a five-year period had a lower risk of cardiovascular disease.
- However, even people with good sleep quality only at one point in the study had a lower cardiovascular risk compared to those with ongoing poor sleep quality.
- The study focused on poor sleep quality, but sleep disorders such as sleep apnea can also increase the risk of cardiovascular disease.
Sleep and health are intimately connected, with poor sleep linked to a greater chance of developing obesity, diabetes, heart disease, depression, and anxiety.
While research shows the importance of high-quality sleep, many studies have looked at people’s sleep patterns at one point in time. But sleep habits can change over the course of a person’s life, so a single measurement may not always show the whole picture for someone’s health over their lifetime.
To gain a better understanding of how changes in sleep patterns affect health, researchers from China examined people’s sleep patterns at two different time points, several years apart.
As with earlier research, they found that higher quality sleep was linked to better health — in this case, a lower risk of coronary heart disease and stroke. These benefits were greatest for people who slept well at the start and end of the study.
However, even people who had high quality sleep only at one point in time saw a lower risk of cardiovascular disease compared to those with ongoing poor sleep quality.
The new study was published April 23 in JAMA Network Open.
How sleep quality affects heart health
The study included over 15,000 retired workers from China who completed questionnaires and had medical examinations about five years apart. Researchers collected genetic data from some people, which was used to determine their cardiovascular risk.
People were excluded from the study if they already had cardiovascular disease or cancer at the start of the study.
Researchers used the questionnaires to determine people’s sleep quality. “Favorable” sleep was based on four factors: bedtime between 10 pm and midnight, sleeping 7 to 8 hours per night, good or fair sleep quality, and napping 60 minutes or less during the day.
Researchers found that people with “favorable” sleep patterns at either point in time were less likely to have a cardiovascular disease event (coronary heart disease or stroke) compared to people with poor sleep patterns at both times.
Even people who had good sleep at the beginning and worse sleep at the follow-up visit had a lower cardiovascular risk compared to those with ongoing poor sleep.
However, people who reported high sleep quality (persistent favorable sleep) at both time points had the lowest cardiovascular risk. This included a 16% lower risk of coronary heart disease and a 34% lower risk of stroke.
When researchers took into account the effect of people’s genes, they found that those with a low genetic risk for cardiovascular disease and favorable sleep patterns at both time points had the lowest cardiovascular risk.
The lowest-risk group had a 35% lower risk of coronary heart disease and a 52% lower risk of stroke compared to people with high genetic risk and ongoing poor sleep.
However, the findings showed that even people with an intermediate or high genetic risk for cardiovascular disease have benefits from good sleep quality, with a 64% lower risk in the good sleep quality group.
So, “even with the presence of genetic factors associated with cardiovascular disease, good sleep quality decreased people’s risk of developing cardiovascular disease,” said Cheng-Han Chen, MD, interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, Calif.
Sleep patterns are often consistent
The results of the new study are similar to earlier research that used survey data to assess people’s sleep quality, said Safia S. Khan, MD, a specialist in sleep disorders and an associate professor in the Department of Family and Community Medicine and the Department of Neurology at UT Southwestern Medical Center in Dallas.
However, the new study is one of the first to look at changes in sleep patterns and the risks from cardiovascular disease over time, she told Healthline.
In another study that assessed sleep quality at two points in time, researchers followed middle-aged European participants for nine years. They found a lower cardiovascular risk for people with higher-quality sleep patterns and for those who improved their sleep habits over time.
These results are similar to the findings in this latest study.
The earlier study also showed that many people have consistent sleep patterns, with only 19% of participants changing their sleep patterns over the course of the study.
“For middle-aged people and retirees, their sleep patterns are not going to change significantly from year to year,” said Khan. “So essentially, we can assume that these people [in the new study] had the same type of sleep pattern before the survey was conducted.”
That means the results of the study are a good indication of the link between cardiovascular outcomes and sleep patterns, she said.
Another unique aspect of the study is that it focused on retired older adults, who may have more natural sleep patterns than middle-aged people, who often adjust their sleep habits to their work schedules, the authors wrote.
Sleep is a key part of heart health
Although the study fits with earlier research, it has certain limitations.
For example, because the participants were all older adults from China, the results may not apply to younger people or those with different racial or ethnic backgrounds.
So “we need to have more studies from other regions of the world,” said Khan, “to see if these results can be replicated in those other areas.”
In addition, this was an observational study, which means “it doesn’t necessarily show that poor sleep quality causes the cardiovascular condition,” Chen told Healthline, only that there is a link between the two.
“It could be that there are other factors, such as depression or stress, that cause both poor sleep quality and cardiovascular disease,” he said.
Researchers didn’t take into account all of these other factors.
For example, “they didn’t look at other aspects of sleep quality that we consider very important,” said Chen, “specifically, sleep disorders such as sleep apnea, which is a risk factor for cardiovascular disease.”
Khan agreed.
“We don’t know how many people had sleep apnea, insomnia, restless legs, or other sleep disturbances,” she said. “Or if their spouses had significant sleep apnea or snoring that could be disturbing [people’s] sleep.”
Although Khan thinks future studies should take into account these other factors, she said we already know that sleep quality is an important aspect of heart health.
The American Heart Association even includes getting healthy sleep as one of its eight essential measures for improving and maintaining cardiovascular health, alongside managing weight, controlling cholesterol, eating better, and staying active.
“Whenever I talk to my patients about cardiovascular health and improving their cardiovascular risk factors, I always mention sleep quality and the idea of getting good sleep, as well as asking if they’ve been checked for sleep apnea,” said Chen.
Takeaway
In a study of over 15,000 retired workers, researchers found that those who maintained good sleep quality over a five-year period had the lowest risk of cardiovascular disease, specifically coronary heart disease and stroke.
However, even people who had good-quality sleep at only one point in the study had a lower risk of cardiovascular disease compared to those with poor sleep throughout the study.
The study relied on questionnaires to assess people’s sleep quality, which may not be accurate. In addition, researchers didn’t assess other factors that can affect cardiovascular disease risk, such as sleep disorders such as sleep apnea and depression.
