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Lack of sleep harms heart response: study

Last Updated: Wednesday, June 13, 2007 | 3:59 PM ET

CBC News

Chronic lack of sleep stresses the heart and may increase the risk of cardiovascular disease and deaths, researchers said Wednesday.

Neurological and behavioural effects of long-term sleep loss are well documented, such as lower concentration and poor mood. Researchers are also uncovering a physiological toll that may increase susceptibility to depression, obesity, cardiovascular disease and diabetes.

In a laboratory study of 39 subjects, Prof. Siobhan Banks of the University of Pennsylvania School of Medicine and her colleagues found people who got five hours of shut-eye for five nights showed significantly less heart rate variability in their electrocardiogram readings.

The findings were presented at the annual SLEEP meeting in Minneapolis, Minn., sponsored by the American Academy of Sleep Medicine.

Heart rate variability is a natural variation in beat-to-beat changes in heart rate that occurs as the body adjusts to stress.

"A reduction in the heart rate variability has been reported in several cardiological and non-cardiological diseases," Banks said in a release.

"If our finding is sustained by a larger group and further analysis, it may suggest why short sleep duration is associated with a heightened risk of cardiovascular disease and mortality."

Previous studies showed shift workers may be at higher risk for cardiovascular disease because their circadian, or sleep-wake, rhythms are disrupted.

Some studies also suggest that reduced heart rate variability helps predict sudden death in heart attack patients, and may be a marker for other heart problems.

In Banks's experiment study, participants got two nights of baseline sleep followed by five nights of sleep loss. Their cardiac function was tested at the beginning of the study and then after the sleep restriction.