December 23, 2012

Sleeping heart

What sleep does for your heart...

Sleep gives your heart and vascular system a much-needed rest. During non-REM (Rapid Eye Movement) sleep, your heart rate and blood pressure progressively slow as you enter deeper sleep. During REM sleep, your heart rate and blood pressure have boosted spikes of activity. Overall, however, sleep reduces your heart rate and blood pressure by about 10 percent.

If you don’t get enough sleep, this nightly dip in blood pressure, which appears to be important for good cardiovascular health, may not occur. According to several studies, if your blood pressure does not dip during sleep, you are more likely to experience strokes, chest pain known as angina, an irregular heartbeat, and heart attacks. You are also more likely to develop congestive heart failure, a condition in which fluid builds up in the body because the heart is not pumping sufficiently.

Failure to experience the normal dip in blood pressure during sleep can be related to insufficient sleep time, an untreated sleep disorder, or other factors. African Americans, for example, tend not to have as much of a dip in blood pressure during sleep. This difference may help to explain why they are more likely than Caucasians to have serious cardiovascular disease.

A lack of sleep also puts your body under stress and may trigger the release of more adrenaline, cortisol, and other stress hormones during the day. These hormones contribute to your blood pressure not dipping during sleep, thereby increasing the risk for heart disease. Inadequate sleep may also negatively affect your heart and vascular system by the increased production of certain proteins thought to play a role in heart disease. For example, some studies find that people who chronically do not get enough sleep have higher blood levels of C-reactive protein. Higher levels of this protein may suggest a greater risk of developing hardening of the arteries (atherosclerosis).

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