Increase the Risk of Heart Disease?
Sleep and the Risk of Heart Disease: How Much is too Little?
When Japanese researchers followed 98,000 middle-aged and older men and women for 14 years, they discovered that participants who slept 4 hours or less each night not only had a greater risk of heart disease but a higher mortality from other causes as well.
To complicate matters, they also found a higher mortality from heart disease and stroke for participants sleeping 10 hours or longer a night compared to those sleeping seven hours nightly. Based on these findings, too little sleep increases mortality, but spending too many hours in bed isn’t heart healthy either. One could conclude from this study that about seven hours sleep is optimal for a healthy heart.
This data is consistent with other recent studies looking at sleep duration and the risk of heart disease, such as the Harvard-run Nurse’s Health Study. This study found that too little sleep is a risk factor for heart disease, but sleeping more than nine hours a night also raises heart disease risk – not to mention the chance of developing other health problems. Sleep is important not only for resting the eyes and the mind but for preventing a host of other chronic diseases from type 2 diabetes and obesity to some types of cancer.
Why Does Inadequate Sleep Increase the Risk of Heart Disease?
No one knows exactly why too little sleep is bad for the heart, although researchers at Emory University have a theory. Their research revealed that levels of c-reactive protein are 25% higher in people who sleep less than six hours a night. C-reactive protein is a marker for inflammation and an independent predictor of a person’s chance of developing heart disease.
According to data from the Women’s Health Study, c-reactive protein levels are a better marker for heart disease risk than even cholesterol levels. Experts believe that c-reactive protein rises when the arteries are chronically inflamed, a condition that can contribute to a heart attack. Lack of sleep seems to send the body into a state of chronic, low-grade inflammation that elevates the risk of a coronary event.
Another theory is too little sleep stimulates release of cortisol. Cortisol, aptly called the stress hormone, not only increases insulin resistance, a risk factor for heart disease but also negatively affects lipid levels, increases blood pressure and raises the heart rate. Recent studies show that cortisol causes endothelial cells lining arteries to dilate and contract inappropriately, a key event in the development of heart disease. Cortisol levels rise when a person is exposed to physical or mental stress and sleep deprivation seems to be a stressful event when it comes to cortisol secretion.
The Bottom Line?
There’s still more to learn about the role sleep plays in heart disease and other chronic diseases. From what we know, there is an optimal level of sleep, which for most people is around 7 to 8 hours a night. Of course, this sleep should be of good quality – tossing and turning most of the night doesn’t count.
If you have problems getting enough sleep, re-evaluate your priorities, and if you suffer from insomnia, there are natural approaches that can help. Don’t neglect sleep – those hours you spend in dreamland could save your heart.
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