Night shift workers significantly more likely to develop AFib, study shows

SHANGHAI, China — Atrial fibrillation (AFib) is the most common heart rhythm disorder affecting millions worldwide. Scientists now say that working late at night may play a significant role in one’s development of the condition.

AFib causes shortness of breath and fatigue and may lead to heart disease. This condition causes the heart to beat abnormally fast – raising the risk of stroke five-fold.

Previous studies have shown that any circumstances that force a person’s internal body clock out of sync can cause a host of metabolic disorders – including cardiovascular disease and cancer. According to new research, night shifts can raise women’s risk of a potentially fatal heart problem by almost two-thirds. Scientists say those who work unsocial hours for over a decade are 64% more likely to develop atrial fibrillation. Male employees with similar routines are over a fifth more prone to AFib.

“Women were more susceptible than men when working night shifts for more than ten years. Their risk increased significantly by 64% compared to day workers,” says co-author Professor Lu Qi, of Tulane University, in a statement.

“People reporting an ideal amount of physical activity of 150 minutes a week or more of moderate-intensity, 75 minutes a week or more of vigorous-intensity, or an equivalent combination, had a lower risk of AF than those with non-ideal physical activity when exposed to a lifetime of night shift work. Thus, women and less physically active people may benefit particularly from a reduction in night shift work,” adds Professor Qi. The implications could be “far-reaching,” as around one-in-five members of the workforce work nights full-time or as part of a rotation.

‘Reducing night shift work may be beneficial for the health of the heart’

The study, based on 283,657 people in the UK Biobank, is the first to investigate the links. Researchers say individuals were more vulnerable to AFib – and other forms of heart disease – the longer and more often they worked nights. Air cabin crew, pilots, restaurant staff, members of the emergency services, and other people with irregular hours may need screening.

“Our results suggest current and lifetime night shift work may increase the risk of AFib. Reducing both the frequency and the duration of night shift work may be beneficial for the health of the heart and blood vessels,” says lead author Professor Yingli Lu, of Shanghai Ninth People’s Hospital in China.

People who currently worked nights had a 12% increased risk of AFib compared to day workers, and for those who have worked nights for at least 10 years, the risk rose to 18%. Likewise, those who worked an average of 3-8 nights per month within the span of 10 years had a 22% increased risk of atrial fibrillation.  

Previous research concludes that shift work raises the risk of cardiovascular disease by 40%. The risk of coronary heart disease was 22% higher in current shift workers. This increases to 37% and 35% respectively for those who had worked shifts for ten years or had a lifetime of 3-8 nights a month.

The study, which includes surveys on employment history, also found that mutations linked to AFib did not affect the link with night shifts. This was regardless of whether participants had a low, medium, or high genetic risk. It also took into account age, sex, ethnicity, education, socioeconomic status, smoking, physical exercise, diet, body mass index, blood pressure, sleep duration, and if someone was a “lark” or a “night owl.”

During an average follow-up period of over 10 years, there were 5,777 AFib cases. This information is from the large study size, with detailed information on over 283,000 people. It’s also the first to link data with genetic information in a population that also has detailed histories available on current shift work and lifetime employment.

“We plan to analyze the association between night shift work and AFib in different groups of people. This may strengthen the reliability of these results and serve as a warning to groups working in certain types of occupations to get their hearts checked early if they feel any pain or discomfort in their chests,” added Professor Lu.

The study is published in the European Heart Journal.

South West News Service writer Mark Waghorn contributed to this report.

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