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Circadian misalignment common in shift workers increases risk for CVD
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Shift workers may be denied the restorative CV benefits of nocturnal sleep due to sleep loss and circadian misalignment, increasing the risk for CVD, according to study findings published in Hypertension.
Daniela Grimaldi, MD, PhD, a research assistant professor at Northwestern University Feinberg School of Medicine, told Cardiology Today that formulating a clinical response to this condition will be difficult.
“Our society needs shift workers,” Grimaldi, who often collaborates with the Sleep, Metabolism and Health Center in the department of medicine at the University of Chicago, said in an interview. “They are essential for many critical services. Furthermore, work demands and social life often mean late evenings. We’ve become a nocturnal society and this may facilitate circadian misalignment and potentially adverse consequences on CV health.”
The study population was 26 healthy people aged 20 to 39 years. Participants were restricted to 5 hours of daily sleep during 8 days. Some had fixed bedtimes — one factor contributing to circadian alignment — while others experienced induced circadian misalignment due to bedtimes delayed by 8.5 hours on 4 of the 8 days.
Grimaldi and colleagues measured daytime ambulatory BP, daytime heart rate and 24-hour levels of urinary norepinephrine — a stress hormone that can constrict blood vessels, raise BP and expand the windpipe — at baseline and at the end of the sleep-restriction period.
Researchers found an increase in 24-hour urinary norepinephrine excretion in the circadian misalignment group vs. the circadian alignment group (30 µg vs. 21 µg, P = .005). All participants had an increased daytime heart rate, with the circadian misalignment group having a greater increase (P = .05). However, there were no changes in BP.
In addition, the circadian misalignment group experienced larger reductions in vagal indices of heart-rate variability during deep-sleep phases (P < .05).
Grimaldi told Cardiology Today that this study, the first of its kind, can prompt more research on the subject.
“The next step is crucial. We must translate the results obtained in the laboratory into real-life conditions,” she said.
Grimaldi said certain steps can be taken to help alleviate this condition.
“If you are a shift worker, which can be about 15% to 30% of the population, try to maintain a good level of physical activity and a healthy diet, and try to sleep enough. At this time, they are the only weapons we have,” she told Cardiology Today. – by James Clark
For more information:
Daniela Grimaldi, MD, PhD,
can be reached at Northwestern University Feinberg School of Medicine, 710 North Lake Shore Drive, Suite 517, Chicago, IL 60611; email: daniela.grimaldi@northwestern.edu.
Disclosure: The researchers report no relevant financial disclosures.
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