Scientists find out why night shifts take a toll on your health

Scientists may have identified the phenomenon that affects and disrupts the health of millions of shift workers who grind throughout the night while the rest of us sleep.

Working while fighting against the body clock may lead to weight gain, diabetes, cancer, depression, and poor heart health, as various studies indicate.

Now, new research has revealed the link between ‘when’ you eat and the impact on your health. The conclusion was driven by a study on rodents, which suggested that a change in appetite behaviour may be seen when sleep-wake cycles and day-night cues don't line up.

A group of scientists at the University of Bristol in the United Kingdom conducted research into the connection between hormones associated with sleep-wake cycles and the daily eating habits of rats. They discovered that disruptions in circadian rhythms (physical, mental, and behavioural changes that follow a 24-hour cycle) had a profound impact on the rats' eating behaviours.

To disrupt the rats' natural bodily rhythms, the researchers administered corticosterone, a hormone similar to cortisol in humans, either in synchrony with or out of phase with the light-dark cues. Corticosterone levels in rodents increase significantly before waking and gradually decrease throughout the day.

Rats with undisturbed rhythms, when exposed to poorly timed corticosterone surges, consumed the same daily amount of food as the rats with in-sync rhythms and a control group that received no infusions. 

However, they ate nearly half of their daily food intake during periods when they would typically be resting.

Additionally, a decrease in genes that suppress appetite likely led to a significantly increased desire to eat during the inactive phase of the rats' day, according to the study.

"When we disturb the normal relationship of corticosterone with the day-to-night light cycle, it results in abnormal gene regulation and appetite during the period of time that the animals normally sleep," University of Bristol neuroscientist and study author Stafford Lightman explained.