Missing a little sleep hurts a lot

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Researchers already know that not getting enough sleep is bad for you. It can increase your risk of high blood pressure, diabetes and gaining weight. Now it appears that it can also increase hardening of your arteries.

Dr. Diane Lauderdale of the University of Chicago Medical Center and her colleagues studied 495 people in their 30s and 40s, fitting them with sophisticated sensors to determine how much sleep they got over a three-night period at the beginning of the study and five years later. They also used electron-beam CT scans at the beginning and end of the study to measure the thickness of the walls of the coronary arteries that deliver blood to the heart.

Over the five years the subjects were monitored, about 12% of those in the study suffered a thickening in the walls of their coronary arteries, an early warning of heart disease, the team reported Tuesday in the Journal of the American Medical Assn. Among those who slept fewer than five hours per night, however, 27% had artery thickening. For those who slept five to seven hours, only 11% developed thickening. And among those who slept more than seven hours a night, only 6% had thickening.

The size of the effect ‘came as a surprise,’ Lauderdale said. ‘It is also something of a mystery’ because researchers have no good idea of the biological mechanism. It is possible there is some yet-to-be-identified factor that decreases sleep duration and increases artery hardening. Or the reduced sleep may mean that average blood pressure levels are higher. Finally, stress or a stress hormone like cortisol, which has been tied to decreased sleep and increased hardening, may play a role.

Or there may be some other reason they have not considered, she added.

Lauderdale conceded that the study was relatively small and said she would like to see it replicated. But considering what is already known about the effects of sleep deprivation, this work simply provides one more reason to try to get a good night’s sleep.

-- Thomas H. Maugh II