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PULLMAN, Wash. — Even just a few days working night shift manages to throw off rhythms in your body that regulate blood sugar, energy metabolism, and inflammation. These findings by researchers at Washington State University help answer more questions about the connection between working irregular schedules and our susceptibility to diabetes, obesity, and other metabolic conditions.
“There are processes tied to the master biological clock in our brain that are saying that day is day and night is night and other processes that follow rhythms set elsewhere in the body that say night is day and day is night,” says senior study author Hans Van Dongen, a professor in the WSU Elson S. Floyd College of Medicine, in a media release. “When internal rhythms are dysregulated, you have this enduring stress in your system that we believe has long-term health consequences.”
Van Dongen adds that the study shows these disrupted rhythms can be seen in just three days, which suggests that early intervention to prevent diabetes and obesity is possible. Intervention may also be beneficial for lowering the risk of heart disease and stroke, which is usually higher in night shift workers, too.
The researchers conducted a controlled laboratory experiment with volunteers who were put on simulated night or day shift schedules for three days. After their last shift, participants were kept awake for 24 hours under constant conditions of lighting, temperature, posture, and food intake to measure their internal biological rhythms without external influences getting in the way. Blood samples were drawn at regular intervals throughout the 24-hour period and were analyzed to identify proteins present in blood-based immune cells.
Some proteins had rhythms closely linked to the master biological clock, which keeps the body on a 24-hour rhythmic schedule. The master clock can withstand varying shift schedules, so these specific protein rhythms didn’t change much on the night shift. However, a majority of the other proteins had rhythms that changed significantly among the night shift volunteers compared to the day shift workers.
Specifically examining the proteins involved in glucose regulation, the researchers noted a nearly complete reversal of glucose rhythms in night-shift participants. Additionally, they found that processes involved in insulin production and sensitivity, which normally work in tandem to keep blood sugar levels in check, were no longer working together in night shift participants. The researchers believe this could be due to the regulation of insulin trying to reverse the glucose changes triggered by working the night shift. They add this could be a healthy response in the short-term because varying glucose levels can damage cells and organs, but it can cause problems in the long run.
“What we showed is that we can really see a difference in molecular patterns between volunteers with normal schedules and those with schedules that are misaligned with their biological clock,” says Jason McDermott, a computational scientist with PNNL’s Biological Sciences Division. “The effects of this misalignment had not yet been characterized at this molecular level and in this controlled manner before.”
The findings are published in the Journal of Proteome Research.
