Cyclical Blood Pressure Patterns Could Offer Critical Health Clues

MINNEAPOLIS, MINNESOTA —  Cyclical patterns in our blood pressure offer clues about risks to our health, according to a medical researcher who first proposed the unorthodox idea that our bodies respond to the natural cycles of day and night, not the hours on a clock.

Although his fellow scientists scoffed at the time, 60 years later circadian rhythms, as Dr. Franz Halberg called these natural cycles, are accepted as a fundamental biological process, and their discovery made the Romanian-born physician famous.

Now, Halberg is challenging medical orthodoxy again.

At a clinic that monitors sleeping habits, Suzi Knowles’ weekly schedule includes two day shifts and two night shifts. While she loves her job, she’s often sleepy.

"The switching back and forth isn’t a good fit for anyone, I don’t think," Knowles says. "I can probably fall asleep within 20 minutes at any point.”

Sleepiness isn’t the only hazard. According to Halberg, now a professor of medicine at the University of Minnesota, many studies indicate shift workers have a higher risk of heart disease and stroke.

Halberg says blood pressure readings could help sort out which workers are at risk and which ones are not. But he says the typical annual blood pressure reading at the doctor’s office offers too little information.

“One reading can tell you that you are still alive, and that’s a good thing to know,” Halberg says.

To know more, says the 93-year-old scientist, you need to measure more often.

Most doctors recommend measuring a healthy person’s blood pressure at least once every year or two.

Halberg checks his every 30 minutes, 24 hours a day, every single day. He says these half-hour measurements, done for at least one week, provide important information about his health, including his patterns of long-term peaks and valleys and sudden spikes that seem to correspond to strain and stress.

But right now, doing this is not easy. Halberg’s own day-in, day-out monitoring device includes a blood pressure cuff, strapped around his upper arm and a pump in his trouser pocket to inflate the cuff for the blood pressure reading. After years of wearing the cumbersome contraption, he hardly notices it.

“I have been wearing it now for 25 years," Halberg says. "And so did [do] a number of my associates around the world.”

Dozens of scientists have sent Halberg a week’s worth of their blood pressure readings, measured every half hour. Some have done this for decades. One for nearly 50 years.

“A distinguished senior professor writes that when he doesn’t have the cuff, he feels naked,” Halberg says.

Halberg calls these researchers test pilots, discovering what long-term monitoring can reveal about health and natural rhythms that range from a few minutes, to months, to decades.

This can be especially important, he says, for people who work shifts that require them to be awake and alert at night.

People like radio announcer Len Houle who has regular hours most of the week, but on Fridays leaves for work at four in the morning.

“It kind of wipes me out a little bit. I’m kind of wasted.” But even worse, he says, was when he was on call at night to provide computer support. “I was usually woken up in the middle of the night, signing onto a computer, and fixing a problem, and then required to go back to bed, which really didn’t work.”

Many shift workers say that it’s easier when they have a consistent schedule so for 10 years, bartender Molly Savory’s been working past midnight, then sleeping late the next morning.

“I’m a night person," she says. "I like to work into the evening hours.”

According to University of Colorado math professor Homer Ellis, he’s done research all night and slept until almost noon for more than 30 years. He feels working a typical 9-to-5 day shift would mess him up.

“I wouldn’t do very well," Ellis says. "No. My schedule fits me.”

But according to Ken Wright, director of a University of Colorado Sleep Lab, feeling good about an unusual shift doesn’t guarantee that it’s healthy.

“We truly don’t understand what makes one person more vulnerable for one negative health outcome versus another," Wright says, "and that’s really a hot area of research that we’re trying to understand.”

Wright says that Franz Halberg has contributed tremendously to understanding the connections between body rhythms and diseases, ranging from heart attack and stroke to diabetes, obesity and cancer.

And while Wright prefers to measure things like blood hormone levels and brain wave patterns, he concedes that more frequent blood pressure tests and closer analysis of the readings could lead to new discoveries.

“I think the science has to drive the questions," Wright says. "But the tools allow us to ask questions.”

Back in Minnesota, Halberg says that one answer is ready and waiting.

“Blood pressure is a life-long [stress] test," he says. "It tells you when you are unhappy, but it also tells you when you are at the risk of heart disease.”

In time, Halberg says, blood pressure monitors will be as cheap and as small as a wristwatch. When that day comes, he says long-term monitoring will be commonplace, and health throughout the world will benefit.