Friday, December 11, 2009

Too Little or Too Much Sleep Harmful

Many of us have heard about the sad demise of Ranjan Das of cardiac arrest in October this year. Ranjan, just 42 years of age, was the CEO of SAP-Indian Subcontinent, the youngest CEO of an MNC in India. He was an unlikely candidate for a heart attack, since he was known to exercise regularly and be scrupulous in his food habits. But he had admitted to not having enough sleep, some say this usually amounted to not more than 5 hours duration each day.

Sleeping either less than 7 hours or more than 8 hours may be a risk factor for an array of common medical problems, including weight gain, diabetes and hypertension (1).

Calcified Arteries and Heart Disease

King et al at University of Chicago Medical Center found that not getting enough sleep increases the risk of clogged up arteries and heart disease (2). Conversely, sleeping well appears to prevent calcified deposits in the coronary arteries supplying blood to the heart.

The five-year study of 495 men and women in their 40s found that light sleepers suffered more artery damage.

Calcified arteries were found in 27 per cent of volunteers who slept less than five hours a night. That figure dropped to 11 per cent for participants sleeping five to seven hours, and six per cent for those who spent more than seven hours asleep. The benefit of one hour of additional sleep was comparable to the gains from lowering systolic blood pressure by 17 mm Hg.

Inflammatory Cytokines and Coronary Artery Calcification

A new study in the journal Sleep suggests that inflammation may be the pathway linking extreme sleep durations to an increased risk for disease. Dr Patel et al.(3)found that sleep duration is associated with changes in the levels of specific cytokines that are important in regulating inflammation.

Cytokines are proteins that are produced by cells. Cytokines interact with cells of the immune system in order to regulate the body's response to disease and infection. Increases in habitual sleep durations are associated with elevations in the cytokines CRP and IL-6 while reduced PSG sleep duration is associated with elevated TNFa levels.

Activation of pro-inflammatory pathways may represent a mechanism by which extreme sleep habits affect health.

Now everybody, just ration yourself to

Not LESS Than 7, Not MORE Than 8 hours sleep a day.

1. Steptoe A, Peacey V, Wardle J. Sleep Duration and Health in Young Adults. Arch Intern Med. 2006;166:1689-1692.
2. King et al. Short Sleep Duration and Incident Coronary Artery Calcification. JAMA, 2008; 300 (24): 2859
3. Patel SR, Zhu X, Storfer-Isser A, Mehra R, Jenny NS, Tracy R, Redline S. Sleep duration and biomarkers of inflammation. Sleep. 2009 Feb 1;32(2):200-4

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