Here is a question for all of us during this Christmas season: Have we been sleeping enough? Should we be making a resolution for the new year to have sufficient sleep (and for those who sleep too much - not to sleep more than 9 hours)?
Who would have thought that how we sleep would turn out to be a coronary artery risk factor every bit as important as smoking or high blood pressure? But that's how it is shaping up. Getting a good night’s sleep prevents coronary artery calcification - the accumulation of calcified plaques in the coronary arteries, a predictor of future heart disease.
A recent study in the Journal of the American Medical Association is making the sleep-heart connection impossible to ignore. Although this is not a brand new discovery, they have demonstrated, with stronger evidence, that as hours of sleep drop toward five or fewer from the eight hours most humans seem to need, the chance of developing coronary disease in young middle-aged men and women grows in close proportion. The JAMA study used a relatively new low-dose CT scanning technique to detect calcium buildup in arteries long before patients have the slightest inkling any plaque is there. Recent studies have found that sleep duration is related with risk factors for coronary artery calcification including glucose regulation, blood pressure, sex, age, education, and body mass index.
To determine whether sleep duration and quality are associated with incidence of calcification, researchers from the University of Chicago followed 495 healthy individuals, aged between 35 and 47 years, for 5 years. The participants completed sleep questionnaires regularly.
Accelerating hardening of the arteries in those skimping on sleep is consistent with many prior observations. For example, people afflicted with chronic loud snoring, a sleep disrupter known particularly to men, experience more heart attacks and higher blood pressure than those who sleep like a baby. And a 10-year study involving 72 thousand middle-aged femal nurses found that those who slept for five or fewer hours a night had a greater chance of suffering heart attacks than similar women who managed a good eight hours of sleep. (Prudence in all things: Getting too much sleep wasn't the best either—with those exceeding nine hours bumping up their heart risk.)
Sure, these studies do not prove causality, but they do offer rather hefty circumstantial evidence of sleep's powers. And for ages, lay instincts have held that sleep is a health potion, with lore ranging from the belief that slumber heals weary bones, to early to bed making one healthy and wise, to sleep being the best face-lift.
The rather novel and surprising strong correlation between sleep deprivation and early coronary artery calcification is compelling enough to change behavior now. After all, the medical intervention is a prescription for more sleep, a therapy that's a pleasure to behold, costs nothing, and comes without side effects. Maybe it's time also to make a seven-to-eight-hour sleep night a serious public-health goal for all in 2009.
More details from the study:
- Ihe incidence of calcification in the heart arteries ranged from 6 percent among the participants who slept more than 7 hours per night, to 11 percent among those who slept between 5 and 7 hours nightly, and 27 percent in those who slept less than 5 hours.
- After adjusting for other factors that might influence the results, such as age, sex, race, education and smoking, one hour more of sleep per night decreased the estimated odds of calcification by 33 percent.
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