Just a few days on a night shift schedule spikes protein rhythms associated with blood glucose regulation, energy metabolism and inflammation, processes that can influence the development of chronic metabolic conditions.
The finding, from a study led by scientists at the University of Washington and the Pacific Northwest National Laboratory, provides new clues as to why night shift workers are more prone to diabetes, obesity and other metabolic disorders.
There are processes linked to the master biological clock in our brains that tell day is day and night is night, and other processes that follow rhythms set elsewhere in the body that tell night is day and day is night. When the internal rhythms are out of whack, you have this constant stress in your system that we think has long-term health consequences.”
Hans Van Dongen, senior study author, professor, WSU Elson S. Floyd College of Medicine
Although more research is needed, Van Dongen said the study shows that these disrupted rhythms can be seen in as little as three days, suggesting that early intervention to prevent diabetes and obesity is possible. Such an intervention could also help reduce the risk of heart disease and stroke, which is also elevated in night shift workers.
Posted on Journal of Proteome Research, the study involved a controlled laboratory experiment with volunteers placed in simulated evening or day shift schedules for three days. After their last shift, the participants stayed awake for 24 hours under constant conditions—lighting, temperature, posture, and food intake—to measure their internal biological rhythms without interference from outside influences.
Blood samples taken at regular intervals during the 24-hour period were analyzed to identify proteins present in blood-based immune system cells. Some proteins had rhythms closely tied to the master biological clock, which keeps the body on a 24-hour rhythm. The master clock is robust to altered shift schedules, so these protein rates did not change much in response to the night shift schedule.
However, most other proteins had significantly altered rates in night shift participants compared to day shift participants.
Looking more closely at the proteins involved in glucose regulation, the researchers observed an almost complete reversal of glucose rates in the night shift participants. They also found that the processes involved in insulin production and sensitivity, which normally work together to keep glucose levels in a healthy range, were no longer synchronized in the night shift participants. The researchers said this effect could be caused by insulin regulation trying to reverse the glucose changes caused by the night shift schedule. They said this may be a healthy response at the moment, as fluctuating glucose levels can damage cells and organs, but could be problematic in the long term.
“What we’ve shown is that we can actually see a difference in molecular patterns between volunteers with regular schedules and those with schedules that are not aligned with their biological clock,” said Jason McDermott, a computer scientist in PNNL’s Department of Biological Sciences. “The effects of this misalignment have not been characterized at this molecular level and in this controlled manner before.”
The researchers’ next step will be to study real workers to determine whether night shifts cause similar protein changes in long-term shift workers.
Source:
Journal Reference:
McDermott, JE, et al. (2024). Molecular-level dysregulation of insulin pathways and inflammatory processes in peripheral blood mononuclear cells by circadian misalignment. Journal of Proteome Research. doi.org/10.1021/acs.jproteome.3c00418.
