The Health Hazards of Shift Work


A long-running study found that women who work overnight have as much as a 60 percent greater risk of developing type 2 diabetes due to irregular sleep patterns and poor dieting.

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"Shift work. Seven to three. Three to eleven. Eleven to seven." So go the lyrics to a popular country song. We live in a 24/7 world where shift work is here to stay in nearly every industry. The paycheck may be padded, but shift workers might be paying a price with their health.

A study published in PLoS Medicine found that women who do shift work have a greater risk of developing type 2 diabetes. Dr. An Pan, a research fellow in the Department of Nutrition at the Harvard School of Public Health, and colleagues used data collected on 177,000 women over 18 to 20 years in the long-running U.S. Nurses Health Study. They found that women who worked rotating night shifts had as much as a 60 percent greater risk of developing type 2 diabetes than women who worked only day and evening hours.

The longer women worked a rotating night shift, the greater their risk of developing diabetes. Those who worked night shifts for one to two years had a five percent increase in risk of developing the disease over the next 20 years. Women who worked nights for 10 to 19 years were 40 percent more likely to develop diabetes, and working a rotating night shift over 20 years pushed the risk to 60 percent.

Body weight has a lot to do with the problem, because overweight and obesity are risk factors for diabetes. The researchers also found that a long duration of shift work may be associated with greater weight gain. Those who work at night are more likely to grab less-than-nutritious food than those who work what are considered normal business hours. Hormones that regulate appetite may be adversely affected by working at night and sleeping during the day.

Compound these dietary factors with the metabolic effects of not sleeping at night, which causes the circadian clock to get out of whack, and the result may trigger a cascade of biological effects that increase the risk of diabetes. The circadian clock helps to regulate both the gastrointestinal and endocrine systems, and sleep disruption contributes to insulin resistance, appetite increase, and weight gain.

In an editorial, Dr. Virginia Barbour, chief editor of PLoS Medicine, said, "If the data from this and other studies are to be taken at face value, shift work has the potential to accelerate the progression of the global epidemic of obesity and diabetes. Obviously, diet is only one component in the pathway to diabetes, but, unlike the metabolic consequences of a deranged circadian rhythm it is potentially amenable to easy intervention."

Barbour argued that unhealthy eating should be considered an occupational hazard and employers should be more proactive -- or required by the government to be more proactive -- in helping employees, particularly shift workers, adopt better eating habits.

Those who work shift work might benefit from spending a little extra time planning meals and snacks when working the night shift. Taking balanced meals to work and tucking healthy snacks into the lunch bag are certainly better for a person's health than pumping quarters into a vending machine when hunger strikes.

The study and editorial were published online in PLoS Medicine.

Image: Roger Jegg -

This article originally appeared on, an Atlantic partner site.

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Beth Fontenot is a registered dietitian and a licensed dietitian/nutritionist. She serves on the Louisiana Board of Examiners in Dietetics and Nutrition and writes for

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