Working night shifts disrupts hormones regulating appetite, study finds

SCIENTISTS have revealed how working night shifts interferes with appetite, hunger and food habits, sometimes resulting in weight gain.

The disruption in the body’s biological clock, or circadian misalignment, brought about by working night shifts affects the hormones which regulate the appetite, the team of scientists, led by the University of Bristol, said. Circadian misalignment is also commonly associated with the phenomenon of ‘jet-lag’.

The team focused on the adrenal gland, situated near the kidney, which produces hormones that control many physiological functions - including metabolism and appetite, called glucocorticoid hormones.

A misalignment between light and dark cues led to a disturbance in the functioning of these hormones, which in turn affected the appetite of the “jet-lagged” group of animals. This led to an increased desire to eat significantly more during the inactive phase of the day, the scientists said in their study, published in the journal Communications Biology.

Their findings reveal how circadian misalignment can “profoundly” alter food habits, to the detriment of metabolic health, the scientists said, adding this research could help the millions of people who work through the night and struggle with weight gain.

The glucocorticoid hormones in the adrenal glands directly regulate a group of brain peptides controlling one’s appetite behaviour, with some increasing appetite (orexigenic) and some decreasing appetite (anorexigenic).

In this study, the “jet-lagged” group’s orexigenic hypothalamic neuropeptides (NPY) became dysregulated, which the authors said may lead to drug treatments adapted to treat eating disorders and obesity. Further, the team discovered that while the control rats ate about 90 per cent of their daily intake during their active phase and only 11 per cent during their inactive phase, the jet-lagged rats consumed about 54 per cent of their daily calories during their inactive phase, with no increased physical activity in this time.

“For those who are working night shifts long-term, we recommend they try to maintain daylight exposure, cardiovascular exercise and mealtimes at regulated hours,” said senior author Becky Conway-Campbell, Research Fellow at Bristol.