Why night shifts may be bad for your liver

Working at night may be bad for your liver as researchers have discovered that this organ adapts to the cycles of feeding and fasting, and the alternation of day and night within 24 hours.

The researchers showed in mice that the size of the liver increases by almost half before returning to its initial dimensions, according to the phases of activity and rest. 

In a study published in the journal Cell, the researchers described how the cellular mechanisms of this fluctuation disappears when the normal biological rhythm is reversed. 

The disruption of our circadian clock due to professional constraints or private habits therefore probably has important repercussions on our liver functions, the researchers said. 

The mice forage and feed at night, while the day is spent resting. 

"In rodents following a usual circadian rhythm, we observed that the liver gradually increases during the active phase to reach a peak of more than 40 per cent at the end of the night, and that it returns to its initial size during the day," said first author of the study Flore Sinturel from University of Geneva.

Researchers showed that the size of liver cells and their protein content oscillate in a daily manner.

The number of ribosomes, the organelles responsible for producing the proteins required for the various functions of the liver, fluctuates together with the size of the cell.

In mammals, the liver plays a pivotal role in metabolism and the elimination of toxins.

But many of us no longer live according to the rhythm of their circadian clock, due to night work hours, alternating schedules or frequent international travels. 

And if mechanisms similar to those found in mice exist in humans, which is likely to be the case, the deregulation of our biological rhythms would have a considerable influence on hepatic functions, according to the researchers.