There’s nothing like a good night’s sleep. The American Academy of Sleep Medicine and the Sleep Research Society recommend seven or more hours of sleep per night on a regular basis for optimal health. But more people, especially women, are getting less of this precious commodity, according to a new study from researchers at the Channing Division of Network Medicine at Brigham and Women’s Hospital in Boston. And their long-term study found a significant increased risk of hypertension in women who sleep less than seven hours on most nights and in women who report symptoms of insomnia.

Insomnia Defined

According to the National Heart, Lung, and Blood Institute, symptoms of insomnia may include difficulty falling asleep, difficulty staying asleep, waking up too early, not being able to go back to sleep, or getting poor-quality sleep. It may also cause sleepiness during the day. The researchers were interested in the effects of long-term insomnia on blood pressure, which is insomnia lasting more than three months that occurs on three or more nights each week.

This specific research uses data from a long-running Harvard study called the Nurses’ Health Study II. This ongoing study has been tracking health data in women nurses for decades. Included in the data are age, diet, lifestyles, physical activity, and blood pressure. In 2001, the study started collecting data on hours of sleep and symptoms of insomnia.

The research team notes that both hypertension and sleep problems are common in the United States. Thirty-five percent of adults do not get adequate sleep, 30 percent have symptoms of insomnia, and 45 percent are living with high blood pressure.

The study included over 66,000 women ages 25 to 42 and covered 16 years of data collection. None of the participants had high blood pressure at the start of the study. During the time of the study, just under 26,000 of the women were diagnosed with high blood pressure. Key findings included…

  • Women who regularly slept less than seven to eight hours or had symptoms of insomnia were at higher risk for hypertension risk factors, including higher BMI, lower physical activity, poor diet, more likely to smoke or drink alcohol, and more likely to have gone through menopause during the study.
  • After adjusting for these other hypertension risk factors, women who slept less than seven to eight hours still had a 10 percent higher risk of being diagnosed with hypertension.
  • Women who reported symptoms of insomnia had a 14 percent higher risk of being diagnosed with hypertension.

Theories on Insomnia Link to Hypertension

Although the exact relationship between hypertension and sleep is not known, the researchers suspect that lack of sleep may cause increased sodium (salt) retention, stiffening of arterial blood vessel walls, and an increased workload for the heart. Disrupted sleep may also influence the control of constriction and relaxation of arteries, called vascular tone. Arteries are the blood vessels that carry blood away from the heart.

The researchers conclude that insomnia or too few hours of sleep is a significant risk factor and could be used as a reason for primary care doctors to screen patients for hypertension. This may help spot the condition before complications of long-term high blood pressure (such as heart failure and stroke) can develop. Although the current study included only women, they hope to continue their research with studies that include men.

Source: Study titled “Sleeping Difficulties, Sleep Duration, and Risk of Hypertension in Women,” by researchers at Brigham and Women’s Hospital, Boston, published in Hypertension.

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