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The Health Risks of Shift Work

WebMD Feature

In the U.S., about 8.6 million people perform shift work, whether they have a night job or rotate shifts during the week. For many, it's a rite of passage in their careers; for others, it's a financial necessity. But there's a growing sense that shift work could be taking a serious toll on their health.

"There is strong evidence that shift work is related to a number of serious health conditions, like cardiovascular disease, diabetes, and obesity," says Frank Scheer PhD, a neuroscientist at Harvard Medical School and Brigham and Women's Hospital in Boston. "These differences we're seeing can't just be explained by lifestyle or socioeconomic status."

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Shift work is also linked to stomach problems and ulcers, depression, and an increased risk of accidents or injury.

The Many Faces of Shift Workers

According to the National Sleep Foundation, a shift worker is not just someone who works nights, but anyone who works outside a steady 9 to 5 schedule.

The millions of shift workers in the U.S. include police officers, firefighters, nurses, doctors, pilots, waitresses, truck drivers, and many more professionals. Even a personal trainer who works out at the gym with clients in the early mornings and evenings is a shift worker.

As shift work has become more widespread in the U.S., the health risks have become a focus both for researchers and for the businesses that employ shift workers. How serious are those dangers -- and can they be reduced? Unfortunately, we don't have all the answers yet.

How Does Shift Work Affect Us?

Experts say that shift work could have a serious impact on our health in at least two ways. Some of it may have to do with the lifestyle that shift work encourages. The rest has to do with our biology.

In terms of lifestyle, working odd hours leads to some obvious problems. People who do shift work tend to have sleep disturbances and sleep loss. They might feel isolated, since their jobs cut them off from their friends and families. They might find it harder to exercise regularly, and may be prone to eat junk food out of a handy vending machine, says Scheer.  

But Scheer and other experts believe a significant part of the problem with shift work is physiological. On a fundamental level, being awake at odd or irregular hours fights with our biological rhythms. Shift work disrupts the circadian rhythm -- our internal body clock that is keyed to natural daylight and darkness.   

Because circadian rhythm affects how the body functions, disrupting it can throw everything out of whack -- including our cardiovascular system, metabolism, digestion, immune system, and hormonal balance. That appears to have serious consequences.

Short-Term Health Effects of Shift Work

The short-term health effects of shift work are clear. Even if you're not a shift worker yourself, you've probably experienced the equivalent effects -- maybe after a transatlantic flight, an all-nighter in college, or a few nights with a wailing newborn. Aside from the obvious fatigue, effects include:

  • Gastrointestinal symptoms like upset stomach, nausea, diarrhea, constipation, and heartburn
  • Increased risk of injuries and accidents
  • Insomnia
  • Decreased quality of life
  • General feeling of being unwell


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