One of the sad facts of life many of us are forced to face as we grow older is the apparently inevitable rise of our blood pressure. Aging arteries stiffen, forcing the heart to work harder, which raises the risk of cardiovascular difficulties. By some estimates, nearly 70 percent of U.S. seniors are living with uncontrolled hypertension, defined by a systolic rate above 130 mm/Hg and a diastolic number above 80 mm/Hg.
I can attest to the fact that pharmaceutical interventions can offer an effective response, and dietary modifications (less sodium and more fiber, potassium, magnesium, and calcium) along with exercise and stress management can also make a difference. But a recent study suggests that adjusting our sleep patterns may lower those numbers as well.
Researchers at Oregon Health & Science University recruited 11 adults, ranging in age from 45 to 62, who had been diagnosed with hypertension and, after monitoring their normal sleep schedules and baseline blood pressure readings for a week, asked them to stick with a specific bedtime for two weeks — and avoid daytime napping. Prior to the study, participants had varied the time they hit the hay each night by an average of 30 minutes. During the two weeks of the observation, they reduced that variability to less than seven minutes. It seemed to make a difference.
On the final day of the two-week trial, participants wore monitors that measured their blood pressure every 20 minutes during the day and every half-hour at night. Researchers found that the more consistent sleep schedule produced lower systolic and diastolic readings — a 4 mm/Hg reduction and a 3 mm/Hg reduction, respectively — over a 24-hour period. Specific nighttime readings showed slightly more promise: a 5 mm/Hg reduction on the systolic scale and a 4 mm/Hg reduction for the diastolic.
Those numbers represent a more significant improvement than what we may think, notes lead study author Saurabh Thosar, PhD, an associate professor of occupational health and science. “The decline in systolic blood pressure of 4–5 mm/Hg over 24 hours and during the night with simply regularizing bedtime for two weeks is comparable to the overall benefits of more than four weeks of regular exercise training or salt reduction, and [regular bedtimes] can thus be considered as an adjunct therapy for blood pressure control,” he writes in the journal Sleep Advances.
The nighttime blood pressure reduction, he adds, has been shown to reduce the risk of cardiovascular events by more than 10 percent in patients diagnosed with hypertension and other comorbidities.
It’s all about circadian rhythms, which govern sleep-wake cycles and regulate cardiovascular function. When the body’s natural “clock” malfunctions due to jet lag, shift work, or illness, the effects are played out at the cellular level, where faltering gene expression or protein output can interrupt the smooth operation of the heart. Maintain a predictable clock, the theory goes, and the cellular mechanism will continue to support healthy cardiovascular operation; let it get out of sync and the heart may malfunction.
Much more research is required to convincingly link sleep patterns with cardiovascular function, Thosar notes, but he’s optimistic that further studies will corroborate his findings and perhaps lead to more effective clinical interventions.
“These improvements encourage randomized controlled trials to investigate this question further and isolate underlying mechanisms,” he notes. “If our results are confirmed and the underlying mechanisms are isolated in larger mechanistic randomized controlled trials, bedtime regularity interventions could be low-cost and highly scalable interventions to reduce cardiovascular risk.”
When I mentioned all this to My Lovely Wife, whose sleep patterns have been reliably unpredictable for as long as I can remember, she seemed less impressed by the results of the study as she was by the apparent ability of the participants to crawl into bed at a prescribed hour and actually get some shuteye.
“Did they really sleep?” she ventured incredulously.
“I guess they did,” I reported.
I don’t know if it was envy or skepticism that accompanied her query, but we quickly pivoted to another, less vexing topic. I could almost imagine her blood pressure rising.
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