Quirks & Quarks

Night shifts put your brain and gut clocks out of whack

Clocks in the digestive system have a 'mind of their own'
Health risks for night shift workers may start in the gut’s timekeepers (Jason Viau/CBC)
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Shocking shift

Night shift workers face increased risks of cancer, heart disease and Type 2 diabetes. Now scientists say the reason may lie in ticking time keepers not in our brain as previously thought, but in the gut.

Working the graveyard shift can wreak havoc on the body's finely-tune rhythms. Just as jet setters who fly across the oceans may feel out of sorts with digestive discomfort, researchers are learning more about how shift works puts our clocks out of whack and can be damaging over the long term.

When we looked at the rhythms in those metabolites we saw something we had never seen before and it was actually it was shocking to us.- Hans Van Dongen

Prof. Hans Van Dongen  is a co-senior author of a new study into how people process food differently during shift work.

The researchers had volunteers follow a simulated night shift schedule in the lab or a day shift for three days. Scientists carefully controlled conditions like light, temperature and feeding schedule so they'd be able to measure what rhythms our bodies produce naturally.

"When we looked at the rhythms in those metabolites, we saw something we had never seen before and it actually was shocking to us," said Van Dongen, a professor in the College of Medicine and director of the Sleep and Performance Research Center at Washington State University. 

If it was midnight in the lab, the brain would be forwarded a couple of hours to 2 a.m., which matches what scientists expected from previous research. But they found signs that the clocks in the gut, liver and pancreas were much further ahead, as if it was noon. 

Elena Skornyakov loads a blood sample into the cold centrifuge at the sleep laboratory at Washington State University. Scientists there explored metabolic disruption from shift work. (Cori Kogan/Washington State University)

"This is so different and so much more profound a shift that we've ever seen before that I was like, 'Wow … This is amazing.'"

Gut's mind of its own

Van Dongen said it's as if the clocks in the digestive system have a "mind of their own."

At the University of Surrey, the study's first author Debra Skene used a new technique to analyze blood samples from the 14 participants. Her team looked for a suite of metabolites, or remnants from digesting food.

Van Dongen said the metabolite findings shed light on why night shift workers might not be able to use glucose, the body's go to source of energy, properly. When the body faces an imbalance of glucose, it can create problems for tissues, muscles and organs.

Meal timing strategy

What's more, he said if metabolites are left in the blood too long then it can cause damage to DNA. If the timing of DNA repair is out whack that could explain why shift workers face an increase risk of getting cancer.

He points to two potential research strategies to help shift workers to adapt:

  • Change the sleep-wake schedule to introduce strategic overnight naps.
  • Shift the feeding schedule so overnight workers eat before they go to bed during the day.

To see which possibility works, researchers first need to tease apart what exactly causes the biological clocks to switch. 

In the meantime, Van Dongen said the findings does add credibility to the general advice overseas travellers get to try to eat and sleep as the locals do as soon as possible.