Sleeping less hurts your heart and your performance

Your co-workers who boast about how little sleep they need (or maybe you’re guilty of that) may want to re-think their water-cooler conversations.

This week, one more study has shown that getting less than six hours of sleep is not something to brag about. It can significantly increase your risk of stroke, heart attack and congestive heart failure. This adds to a growing body of research that getting inadequate sleep can not only increase your risk of a number of health problems including obesity, diabetes, and high blood pressure, but can hurt your performance at work as well.

The latest findings were presented at the American College of Cardiology's annual meeting. Researchers studied approximately 3,000 patients over 45 years of age, placing them into three categories of sleep: those who slept less than 6 hours a night, those who got six to eight hours of sleep, and those who slept more than eight hours a night on average.

“Those who slept under six hours were two times more likely to have a heart attack and stroke and 1.6 times more likely to have heart failure,” says the study's principal investigator Dr. Rohit Arora, chairman of cardiology and professor of medicine at the Chicago Medical School.

The study also found that sleeping more than eight hours is not great for your heart, raising the risk of angina (chest pain) and coronary artery disease.

“We’re not sure if the extra sleep is contributing to these problems because we know that people who sleep longer tend to have other conditions like obesity, diabetes and other illnesses that may also raise their risk of heart disease,” Arora said.

The researchers didn’t look at why too little sleep is not good for your heart, but previous studies have linked insufficient sleep to increased levels of stress hormones and inflammatory markers.

“These substances may be causing damage to the blood vessels of the heart and brain,” Arora said.  Too little sleep has also been linked to glucose intolerance, diabetes and high blood pressure—all risk factors for heart disease.

And, that’s not all. Past studies have shown people who slept four to six hours a night showed a decline in the ability to sustain attention, a factor that can affect the quality of your work and productivity.  This ability to sustain attention worsened with each night of shortened sleep. After two weeks of little sleep, subjects scored five times lower on psychomotor scales than those who got eight hours of sleep.  Ironically, most people don’t recognize their lagging performance.

In this study, the short sleepers insisted that their performance hadn’t suffered, while their testing showed it clearly had.

“Our recommendation would be that the ideal amount of sleep should be between six and eight hours of good quality sleep,” Arora said. “This may be more important for people who have underlying heart disease."

Laurie Tarkan is an award-winning health journalist whose work appears in the New York Times, among other national magazines and websites. She has authored several health books, including "Perfect Hormone Balance for Fertility." Follow her on Twitter and Facebook.