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New research suggests that working long hours at night may increase the risk of developing an irregular heart rate, a condition known as atrial fibrillation. Cecilie Arcurs/Getty Images
  • According to a new study, people who work night shifts have a 12 percent higher risk of atrial fibrillation (AFib), an irregular heart rate, compared to people who work during the day.
  • While the study does not establish a causal link between working at night and Afib, researchers say the results suggest an increased risk factor.
  • AFib is an extremely common heart arrhythmia, that left untreated, can lead to heart failure and stroke.

Working night shifts over an extended period of time may raise the risk of atrial fibrillation (AFib), a common heart arrhythmia.

A study published in the European Heart Journal found that when compared with daytime workers, people who worked night shifts had a 12 percent higher risk of AFib, an irregular heart rate.

“Although a study like this cannot show a causal link between night shifts and atrial fibrillation and heart disease, our results suggest that current and lifetime night shift work may increase the risk of these conditions,” Yingli Lu, study co-leader and a researcher at Shanghai Ninth People’s Hospital and Shanghai JiaoTong University School of Medicine, said in a press release.

“Our findings have public health implications for preventing atrial fibrillation. They suggest that reducing both the frequency and the duration of night shift work may be beneficial for the health of the heart and blood vessels,” Lu said.

In undertaking the research, Lu and colleagues examined data of more than 283,000 people from the UK Biobank. They found the risk of AFib increased by 18 percent for people who had been working night shifts for their entire careers.

Lu and colleagues also found a 22 percent increase in risk in people who had worked 3 to 8 night shifts per month on average for a period of 10 or more years

Dr. Parveen Garg, a cardiologist with Keck Medicine at the University of Southern California, says the results of the study aren’t surprising, as the lifestyle that may accompany night shifts can increase risk of atrial fibrillation.

“When people have to work nontraditional hours, it can lead to a less healthier lifestyle that can cause you to be more sedentary. It’s harder to exercise,” Garg said.

“We know that people who work nontraditional work hours develop metabolic abnormalities like impaired fasting glucose, which can lead to diabetes. They tend to be more overweight… it’s harder to eat properly when you’re eating at off hours,” Garg told Healthline.

“When we’re talking about diabetes and obesity and physical inactivity and perhaps development of high blood pressure, these are all really strong risk factors for atrial fibrillation,” he said.

AFib is the most common form of a heart arrhythmia. The condition causes an irregular heart rate in the upper part of the heart, meaning blood doesn’t flow in a typical way to the lower chambers of the heart.

For some people, AFib will happen only for a brief time, but for others it can be a permanent condition. If left untreated, the condition can lead to heart failure and stroke.

According to the Centers for Disease Control and Prevention (CDC), AFib was listed on more than 175,000 death certificates in 2018.

The CDC estimates that by 2030, more than 12 million Americans will have this form of heart arrhythmia.

Dr. Megan Kamath, a cardiologist at UCLA, says there are many factors that could contribute to AFib.

“There are a number of different potential causes for AFib, including high blood pressure, heart disease, previous heart attack, congenital heart disease, heart failure, infections, thyroid problems, sleep apnea, lung disease, obesity, smoking and other substance use,” Kamath told Healthline.

The risk for AFib increases as people get older and as women typically live longer than men, they are more likely to experience the condition.

In the study published in the European Heart Journal, the researchers found that when compared with men, women were at higher risk of AFib when they worked night shifts for more than 10 years. Their risk increased by 64 percent compared with their peers who worked in the day.

But Garg emphasizes that the study did not find a definitive link between AFib and night shifts.

“It’s not a strong association. It is suggesting that there is some relationship, but we can’t really say that it is a robust one,” he said.

“I don’t think the answer here is if you’re working night shifts that you need to scramble to find another job where you don’t work night shifts, or you need to try to figure out a way to reduce your night shifts in the job you currently have,” Garg said.

“The emphasis should be trying to encourage or help these individuals in managing their risk factors and eating better and exercising, and managing the stress better so they can reduce their risk of not only for atrial fibrillation but even heart disease,” said Garg.

Kamath says night shift workers can do a number of things to protect their health.

“Things like clustering night shifts together, improving sleep hygiene, maintaining good nutrition, and exercise can help,” she told Healthline.

“Staying healthy and visiting your healthcare provider for routine health maintenance is a great start, as we can work together to prevent problems with heart health before they start,” said Kamath.