Reviewed by William Blahd on November 16, 2015


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Dr. Sandra Fryhofer: Hello. I'm Dr. Sandra Fryhofer. Welcome to Medicine Matters. The topic: shift work. And increased risk of heart attack. A new study in the British Medical Journal[1]. Here is why it matters.

Dr. Sandra Fryhofer (Continued): Night shifts, split shifts, casual shifts, on-call shifts. A lot of people, including most healthcare professionals, don't work a regular 9-to-5 job. And if you have an irregular schedule that's anything other than regular daytime hours -- this study is for you.

Dr. Sandra Fryhofer (Continued): This meta-analysis combines 34 studies, involves more than 2 million people, and links shift work to an increased risk for heart attack and stroke.

Dr. Sandra Fryhofer: This meta-analysis combines 34 studies and involved more than 2 million people, and links shift work to an increased risk of heart attack and stroke. This the largest ever look at shift work and cardiovascular risk. Risk of heart attack was increased by 23%, risk for stroke was increased by 5% as compared to regular daytime workers.

Dr. Sandra Fryhofer (Continued): The worst shift for your heart, not surprising, is the night shift. A 41% increase in heart attack risk. Slightly reassuring, shift work was not associated with an increased risk of death; not from heart attack, not from stroke, not from any cause.

Dr. Sandra Fryhofer (Continued): Previous studies have linked shift work to increased risk of high blood pressure, metabolic syndrome, high cholesterol, and diabetes. Now, this study shows increased risk of cardiovascular events. In fact, even doing just 1 overnight shift increases blood pressure and affects heart rate.

Dr. Sandra Fryhofer: We know that shift work disrupts the circadian rhythm. It interferes with sleep and affects work-life balance. Also, shift workers are more likely to smoke. But, increases in vascular events were seen even in studies that took into account and adjusted for unhealthy behaviors.

Dr. Sandra Fryhofer (Continued): A study looking at military women working night shifts found they had an increased risk of breast cancer, so effects of disrupting circadian rhythm go much deeper than disturbed sleep. What are the public health implications of this study?

Dr. Sandra Fryhofer: Shift workers need careful monitoring of risk factors, like high blood pressure and high cholesterol. Patient education and awareness of cardiovascular risk factors and recognition of symptoms are also important.

Dr. Sandra Fryhofer (Continued): For Medicine Matters, I'm Dr. Sandra Fryhofer.