Researchers gain new perspective on how shift work disrupts metabolism

SPOKANE, Wash. - A new study led by Washington State University Elson S. Floyd College of Medicine researchers revealed the biological clocks in people's digestive organs are "profoundly and quickly" changed by shift work schedules. 

Studies have shown that working night shifts or other unusual work schedules increases the risk of becoming obese and developing other metabolic disorders, which in turn can raise the risk of heart disease. This WSU study has moved scientists closer to finding out why that happens.

Experts previously thought the metabolic disruption in shift workers was driven primarily by the brain's master clock. This study revealed otherwise.

"We now know that shift work rapidly changes the clocks in the digestive track that are responsible for our metabolism and this is one of the reasons that shift workers experience metabolic problems," said Sleep and Performance Research Center Director Dr. Hans Van Dongen.

According to WSU, the study included 14 participants who each spent seven days inside the sleep laboratory at the WSU Health Sciences Spokane campus. First, half of them did a three-day simulated night shift schedule, while the rest were on a three-day simulated day shift schedule. Then, participants were kept in a constant routine protocol used to study their internally generated biological rhythms. 

During the protocol, researchers tested the volunteer's blood. They analyzed 132 different metabolites related to metabolism and the digestive system. 

They found that after the night shift schedule, separate biological clocks in the liver, gut, and pancreas react differently than the brain's biological clock. 

Kootenai Health Registered Nurse Robert Mendenhall said there is a need to address working conditions, expectations, and dangers to long, unusual hours. 

"It's almost worn as a badge of honor that somehow sacrificing yourself and the body for the long term is somehow seen as a strength," Mendenhall said. "There are institutional and process changes that need to be put in place to assist the nurse to help regulate. We can't do it on our own."

Those changes may one day be influenced by this WSU study. 

Meantime, Van Dongen said the next step in research is to find out what causes the shifted metabolite rhythms. Research indicated it could be the altered sleep/wake schedules, the different timing of when people eat, or both. Understanding that will allow scientists to pinpoint the underlying cellular and/or hormonal processes, which in turn could support new treatments to prevent negative long-term health consequences, according to Van Dongen. 

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