Biorhythm
New study shows why night work makes you fat
Rework messes up your internal clock.
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If you work at night, you mess up your internal clock. The hormonal cycle and the light-dark rhythm no longer match. During the day, when you should be sleeping, messenger substances in the brain stimulate your appetite.
All living things have an internal biological clock that is coordinated with the 24-hour day. This rhythm controls a whole range of processes: Hormones, blood pressure, appetite and sleep cycle.
Weight gain, diabetes, cancer, depression and poor heart health are common among shift workers who fight their body clock to stay awake. Scientists at the University of Bristol now wanted to know what actually happens in the body when normal processes are disrupted.
Experiment with rodents
For the study, they put the internal clock in a group of rats under stress. They paid particular attention to changes in appetite and eating behavior.
In the experiment there was a group of rats that were left alone. The control group. The others were treated like night workers and suffered from jet lag. The result: The night shifts messed up the animals’ eating habits. Instead of resting during the inactive phase – which now fell on the day – they ate.
A hormone was responsible for this. “The adrenal hormone corticosterone, which is normally released circadian (24-hour rhythm), is an important factor in the daily control of brain peptides that regulate appetite,” said Stafford Lightman, Professor of Medicine at Bristol Medical School and Co -Senior author of the study. “If we disrupt the normal relationship of corticosterone with the day-to-night light cycle, this results in abnormal secretion and appetite during the time when animals normally sleep.”
The comparison to the control group was clear. The rats, with the usual rhythm, only consumed 11 percent of their daily food during the resting phase. In the case of jet lag rodents, this value shot up to 58 percent. Lightman said when we disrupt our normal body rhythms, it disrupts normal appetite regulation because adrenal hormones are attuned to the light-dark cycle.
Disturbance of the internal clock
Dr. Becky Conway-Campbell, the study’s lead author, said: “For people who work all night long, a reversed body clock can have devastating effects on their health.”
She assumes that the health of night shift workers is damaged. “For people who regularly work night shifts, we recommend the following. They should try to maintain daylight exposure, cardiovascular exercise and meals at regular times.” In practical terms, it may be difficult to enjoy bright sunlight when the active phase falls at night. Someone who always works nights can at least maintain a consistent meal schedule. However, if the person works alternating shifts, this is hardly possible.
Dr. Conway-Campbell is also aware that it is “difficult to counteract hormonal messages in the brain with ‘discipline’ or ‘routine’.” Presumably only medication can slow down the hormonal hunger impulse. However, night work would then be accompanied by long-term medication.
source: Communications Biology