How can lack of sleep contribute to heart disease?

Sleep deprivation causes an imbalance in chemicals, such as cortisol, epinephrine, norepinephrine, and magnesium. These chemicals are important messengers for the autonomic nervous system, which controls automatic body functions like heart beat and breathing. Even in healthy people, an imbalance in these chemicals from sleep deprivation can cause a strain on the heart. Sleep loss also increases chemicals that cause inflammation, which is another important risk factor for heart disease, as well as arthritis and diabetes.

The effects of sleep deprivation on the heart were studied in a group of over 70,000 nurses, who were followed for ten years. Among these women, those sleeping five or fewer hours each night had almost twice the risk of experiencing heart disease compared with women sleeping eight hours at night.

A number of studies have linked short-term sleep deprivation with several well-known risk factors for heart disease, including higher cholesterol levels, higher triglyceride levels, and higher blood pressure. One such report, published in an issue of Sleep, included more than 98,000 Japanese men and women ages 40 to 79 who were followed for just over 14 years. Compared with women who snoozed for seven hours, women who got no more than four hours of shut-eye were twice as likely to die from heart disease, the researchers found.

A shut-eye shortfall has been linked to increased calcium deposits in the heart's arteries, according to a study in The Journal of the American Medical Association. Sleep deprivation boosts blood pressure, inflammation, and stress hormones, which may explain the association.