For a healthy heart, sleeping 6 to 7 hours each night is best

DETROIT — It’s no secret that getting the right amount of sleep each night plays an important role in one’s mental and cognitive health. New research now shows that sleeping six to seven hours a night also reduces the risk of a heart attack or stroke.

In fact, researchers from the Henry Ford Hospital say that people who manage less — or more — are more prone to cardiovascular disease.

“Participants who slept less than six hours or more than seven hours had a higher chance of death due to cardiac causes,” says lead author, Dr. Kartik Gupta, a resident in the hospital’s Division of Internal Medicine, in a statement.

Levels of an inflammatory marker called CRP (C-reactive protein), which is linked to heart problems, were also raised in those with longer or shorter durations of sleep. The results are consistent with the idea that sleeping around seven hours a night is optimal.

Kartik and his team adds to mounting evidence that sleep, in addition to diet, smoking habits and exercise, is vital to cardiovascular health. It helps clear the body of toxic proteins that can trigger a host of conditions, including high blood pressure and hardening of the arteries.

“Sleep is often overlooked as something that may play a role in cardiovascular disease,” says Gupta. “It may be among the most cost-effective ways to lower cardiovascular risk. “Based on our data, sleeping six to seven hours a night is associated with more favorable heart health.”

Looking at heart health markers across groups of participants

This latest study analyzes data on 14,079 people who participated in the 2005-2010 National Health and Nutrition Examination Survey. They were tracked for about eight years to determine if they died due to heart attack, heart failure or stroke. Their average age was 46, and fewer than one in ten had a history of heart disease, heart failure or stroke.

The participants, evenly split between the sexes, were divided into three groups depending on average length of sleep. Levels of CRP and atherosclerotic cardiovascular disease (ASCVD) risk scores were then assessed. The latter is widely used to predict death from heart attack, stroke or hardening of the arteries (atherosclerosis) over the next ten years.

It’s based on age, gender, race, blood pressure and cholesterol. A score of less than 5 percent is considered low risk.

The overall average ASCVD risk was 3.5 percent, with the lowest among those having six to seven hours sleep a night. For those having less than six it was 4.6 percent, compared to 3.3 percent for six to seven and more than seven.

“ASCVD risk score was, however, the same in those who sleep six to seven hours versus more than seven hours,” says Gupta.

It may not adequately capture elevated risk in this subgroup, with results perhaps stronger for those sleeping less than six hours a night, he adds.

Amounts of CRP, a protein made in the liver that rises when there is inflammation in the body, were also higher in those with longer or shorter durations of sleep.

“Participants who sleep less or more than six to seven hours have higher ASCVD risk scores, which is likely driven by heightened inflammation as measured by CRP, which was found to be higher among those who had less or more sleep,” says Gupta.

He points out that it was only measured at the start of the study. “The effect of sleep probably accrues over time; it takes time for the damage to happen,” he adds.

Gupta says the individuals were limited to choosing hour blocks — such as six, seven or eight hours — when noting sleep time. But the findings stood after taking other factors into account like lack of exercise, smoking and an unhealthy diet, all known to damage the heart.

Sleep quality discussion should be a part of every visit to the doctor

While some risk factors for heart disease, such as age or genetics, can’t be changed, one’s sleep habits can be adjusted and should be routinely asked about during medical visits.

“It’s important to talk about not only the amount of sleep, but the depth and quality of sleep too,” says Gupta. “Just because you are lying in bed for seven hours doesn’t mean that you are getting good quality sleep.”

For example, sleep apnea, a breathing disorder that causes snoring and results in frequent awakenings, is increasingly linked with cardiovascular disease.

The findings conflict with messaging from the Centers for Disease Control and Prevention, which recommends adults log at least seven hours of sleep each night “for the best health and wellbeing.” They find that adults who don’t meet this standard are more likely to report 10 chronic health conditions compared to those who do. They’re also more likely to be obese, physically inactive, and smokers.

Similarly, the National Sleep Foundation and the American Academy of Sleep Medicine recommend most adults get seven to nine hours or seven or more hours of sleep a night, respectively.

Dr. Gupta calls for more research to further validate them. Previous studies suggest sleeping less than five hours a night — or more than eight — is harmful to heart health.

SWNS writer Mark Waghorn contributed to this report.