Just three days of working night shifts causes disruption to the internal rhythms linked to the regulation of blood glucose, which can increase the risk of developing diabetes.
That is the finding by researchers in America who investigated why people who work through the night are more disposed to developing diabetes, obesity and other metabolic disorders.
They found that working nights disrupts protein rhythms which are also linked to energy metabolism and inflammation, processes that also play a role in the development of chronic metabolic conditions.
With these changes seen in as little as three days, the research team say that early intervention could help to lower the risk of developing diabetes and obesity.
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Senior study author Hans Van Dongen, a professor at Washington State University, said: “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.
“When internal rhythms are dysregulated, you have this enduring stress in your system that we believe has long-term health consequences.”
The study involved a group of volunteers who were put on simulated night or day shift schedules for a period of three days. After their last shift, the volunteers were kept awake for 24 hours so the research team could record and measure their internal biological rhythms.
Throughout this 24-hour period, blood samples were taken to identify proteins present in blood-based immune system cells.
The master biological clock keeps the body on a 24-hour rhythm, and is robust against changes to shift schedules. This means that the proteins with rhythms closely linked to the master clock don’t alter much.
What the researchers found, however, was that most proteins’ rhythms altered significantly in those volunteers on the night shift schedule, compared to those on the day shift schedule.
In particular, the team found that in night shift volunteers, there was a nearly complete reversal of glucose rhythms in the proteins linked to glucose regulation.
Another key finding was that the processes involved in insulin production and sensitivity were no longer synchronised in the night shift volunteers.
They are normally synchronised to ensure glucose levels stay within a healthy range.
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This could be a result of the body regulating insulin as it attempts to reverse the glucose changes which occur as a result of the night shift schedule. While this is a normal response in the short term, it could cause problems in the longer term, the researchers say.
Jason McDermott, a computational scientist with Pacific Northwest National Laboratory, said: “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.
“The effects of this misalignment had not yet been characterised at this molecular level and in this controlled manner before.”
Read more in Journal of Proteome Research.
