A good sleep curbs inflammation that harms heart

Poor sleeping habits have long been linked to unhealthy hearts, but the mechanism behind it has never been fully understood.

Now Prof Matthew Walker, a sleep expert, and his team have discovered that plaque accumulates inside arteries of poor sleepers causing inflammation.

Two white cells, called neutrophils and monocytes, gather in the arteries of those with patchy sleep. The cells cause inflammation, known as atherosclerosis, increasing the risk of strokes and dangerous heart conditions, the team found.

Researchers hope their findings will contribute to public awareness about the dangers of poor sleep. It is recommended that adults should sleep for between six and nine hours a night.

Experts believe it gives the body a chance to repair cells and blood vessels, clear out waste and boost the immune system.

Walker, the author of international bestseller and Why We Sleep an academic at the University of California, Berkeley, said: “Improving sleep may offer a novel way to reduce inflammation and reduce the risk of atherosclerosis. These findings may help inform public health guidelines that seek to increase the continuity of sleep as a way to improve health and decrease the burden of heart disease on society.”

To measure sleep disruption over a number of nights the researchers used both lab-based polysomnography, which records brain waves, blood oxygen level and heart rate during sleep, and a simple movement detector worn on the wrist.

The team used standard blood cell counts to measure levels of neutrophils and monocytes. They discovered that fragmented sleep, as measured by the wrist detector, produced higher neutrophil counts and higher coronary artery calcium, a measure of inflamed arteries.

In short, poor sleep led to increased neutrophils, which in turn led to inflamed arteries and worsened atherosclerosis.

Even after accounting for known contributors to artery disease, including age, sex and body mass index, sleep disruption was still found to aggravate inflammation.

Walker added: “These results provide a mechanism to explain the long-standing observation that poor sleep increases the risk of heart disease and stroke, and suggest simple and direct ways to reduce such risk.”

The finding, published in the PLOS Biology journal, suggests that asking patients about their sleep may be a useful tool for assessing their sleep-related risk of heart disease.

The research follows a study published last month by US researchers at the University of Notre Dame in Indiana, who studied the correlation between bedtime regularity and resting heart rate using Fitbit data.

They found that people going to bed even 30 minutes later than their usual bedtime presented a significantly higher resting heart rate that lasted into the following day.

An increased heart rate means an increased risk to cardiovascular health, Prof Nitesh Chawla, the lead study author, said at the time.

Experts suggest that those looking to get a good night’s sleep should avoid using smartphones, tablets or other electronic devices for an hour before bed as the screen light “may have a negative effect on sleep” and if insomnia lasts more than four weeks, you should contact your GP.

Improving sleep may offer a novel way to reduce inflammation and reduce the risk of atherosclerosis