Published: April 06, 2008 10:55 pm         

Don’t let high BP catch you napping

Terri, 47, got up at 5:30 every morning so she could run five miles on the treadmill before getting ready for a long day at the office. She was normal weight and her diet was generally low-fat, so she was shocked when her blood pressure started creeping above 130/85.

Her doctor inquired about her stress at work (it was substantial) and her sodium intake (she was eating a lot of prepared food as she rushed from appointment to appointment). And when he asked how much sleep she was getting, she had to admit it was less than five hours a night. All of those factors may have been contributing to her elevated blood pressure.

Blood pressure is not a constant but fluctuates constantly — rising with strenuous activity or excitement and falling with rest. A diagnosis of high blood pressure must be made on an average of many readings over an extended period.

Normal blood pressure is anything under 120/80, and when readings creep higher, it’s usually a sign lifestyle changes are needed. Otherwise, blood pressure will continue to increase and produce harmful changes in the heart and blood vessels.

Blood pressure that’s consistently elevated is a silent killer, it rarely produces symptoms, yet is a major risk factor for heart attack, stroke and kidney failure.

The effect of sleep on blood pressure — or any aspect of health — has not been well studied, but that is changing.

A 2006 study published in Hypertension found lack of sleep increased the risk of hypertension. Researchers found persons who slept five hours or less a night tended to have higher heart rate and blood pressure, setting them up for health problems.

The researchers stressed the results do not prove the subjects’ sleep habits affected their blood pressure. But they do illustrate the need for more study.

These subjects exercised less and were more likely than other subjects to be overweight and to have diabetes or depression. Other studies have indicated lack of sleep tends to increase appetite and make cells less sensitive to insulin.

For Terri, the issue was rest. Sleep is a time when the heart has a chance to slow down. Under normal conditions, both heart rate and blood pressure drop for an extended period.

One major reason many Americans have inadequate sleep — often without their knowledge — is sleep-disordered breathing or sleep apnea. The person with sleep apnea stops breathing for 10 seconds or longer hundreds of times a night that typically end with a snorting sound.

A study of 140 children using portable blood pressure monitors worn 24 hours a day found those with sleep-disordered breathing had significantly higher blood pressure and signs of thickening of the left ventricular wall of the heart — structural change often associated with hypertension that can lead to serious heart problems including congestive heart failure.

One reason heart attacks tend to occur during the morning hours may be most individuals experience a steady increase of blood pressure at this time following a night of sleep. Children with sleep disordered breathing had higher than normal morning surges of blood pressure.

Treatment of sleep apnea involves night-time use of a mask that provides continuous positive airway pressure (CPAP).

The normal diurnal pattern is for blood pressure to “dip” or decline by 10 to 20 mmHg each night between 8 p.m. and 2 a.m. and then start rising throughout the early morning due to an increased production of hormones that causes a tightening of blood vessels throughout the body.

Non-dippers have an increased risk of blood-pressure-related damage to the heart, brain and kidneys. But persons who have an extreme dip (a decrease of 20 percent or more) during the night may also be at risk of problems related to the morning surge of blood pressure. An extreme surge of blood pressure in the morning hours is a strong predictor of stroke.

Most of us have no clue what our blood pressure is during sleeping hours, and the only way of finding out is through use of an ambulatory blood pressure monitor, which may not be needed. A more important strategy is focusing on what you can control: Getting a good night’s sleep — seven to eight hours every night, lowering your salt intake and taking medications your doctor prescribes for hypertension.



Rupp is information and assistance case manager with the Northern Oklahoma Development Authority Area Agency on Aging.