Study finds the time of day can increase the risk of dying from sudden cardiac death

Friday, April 06, 2012 by: J. D. Heyes
Tags: sudden death, heart attack, time of day

(NaturalNews) So far, no one has been able to accurately predict the day, month and year we'll depart this earth, but scientists have at least been able to narrow down the time of day when it's most likely. Sort of.

In a new study published in the research journal Nature, scientists have found that you're more at risk of "sudden cardiac death" in the morning, with your risk rising again in the evening. Here's why.

The body works on a 24-hour clock, which is called the Circadian rhythm. Essentially, it's your body's way of keeping itself in sync with its surroundings. Jet lag is a perfect example of the body getting out of sync.

At various times of the day so-called "clock genes" tell the body when to produce proteins, and the level of these proteins rise and fall in rhythmic patterns.

"These oscillating biochemical signals control various functions, including when we sleep and rest, and when we are awake and active," says a description of the process by The University of Utah. "Circadian rhythms also control body temperature, heart activity, hormone secretion, blood pressure, oxygen consumption, metabolism and many other functions.

"Clock genes send out instructions that dictate protein production," says the description. "The genes interact with each other to produce daily fluctuations in the amount of proteins produced."

In the study, U.S. scientists found that as these chemical changes occur throughout the day, they can have an impact on your health. These changes led them to identify, in mice, how time of day can ultimately increase your risk of sudden cardiac arrest.

Isolating the protein culprit

Scientists identified a protein called kruppel-like factor 15 (Klf15), whose release is controlled by the internal body clock and whose levels change during the day. Specifically, Klf15 influences the ions which control your heart rate.

Genetically modified mice that either produced too much Klf15 or none at all both had increased risks of developing a deadly heart arrhythmia.

"Our study identifies a hitherto unknown mechanism for electrical instability in the heart," Prof. Darwin Jeyaraj, of the Case Western Reserve University School of Medicine in Cleveland - one of the nation's top medical schools - said. "It provides insights into day and night variation in arrhythmia susceptibility that has been known for many years."

Accounting for the differences between the way hearts in mice and human beings function, it's not clear if the same chemical changes occur in people, the study said. Nonetheless, the research thus far has been promising in terms of understanding the body's chemical changes related to its Circadian rhythm.

'Blooming obvious'

"We are just scratching the surface. It might be that, with further study, assessment of circadian disruption in patients with cardiovascular disease might lead us to innovative approaches to diagnosis, prognosis, and treatment," fellow researcher Prof. Mukesh Jain told the BBC.

Others see similar promise in the findings.

"It's a great paper, it gives a beautiful molecular mechanism which explains a phenomenon that's been kicking around for a long time," Dr. Michael Hastings, of Britain's Medical Research Council's Laboratory of Molecular Biology, said.

The most important aspect of the research, he said, was translating the results into usable medical practice and "targeting the most vulnerable stage" of the cycle, like slow-release blood pressure medications that are most effective first thing in the morning, when cardiac risk is highest.

"When you think about it, it's so blooming obvious," Hastings said.

Sources for this article include:

http://www.bbc.co.uk/news/health-17127649

http://www.nature.com

http://learn.genetics.utah.edu/content/begin/dna/clockgenes/