Study reveals why working at night is dangerous for your health

A new study on rodents has identified a hormonal mechanism that can lead to changes in appetite when sleep-wake cycles and day-night cues are not aligned.

science study sleep work night health
© Beth JNR / Unsplash
science study sleep work night health

According to a 2012 study by the French Ministry of Employment, 15% of employees work at night, i.e. between midnight and 5am. Weight gain, diabetes, cancer, depression and cardiovascular problems are common among workers who fight their biological clocks to stay awake to work, as the body's normal circadian rhythms are disrupted.

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Night work favors eating disorders

Nurses, security guards and other workers accustomed to night shifts know better than anyone how difficult it can be to follow some of the advice offered to preserve one's health: sun exposure, exercise, eating at set times...

A team of researchers from the University of Bristol, UK, recently discovered a link between hormones linked to sleep-wake cycles and daily eating habits, using lab rats. They found that disruption of circadian rhythms had a profound impact on the eating behavior of these animals.

Corticosterone is to rodents what cortisol is to humans: a glucocorticoid hormone which rises sharply in the hours before awakening and then falls steadily throughout the day.

Rats whose sleep rhythms were disrupted by corticosterone spikes consumed the same amount of food each day as the synchronized animals and a control group of rats that received no infusion. But they consumed almost half their daily food intake at times when they would normally have been resting.

Although this change of pace is not associated with weight gain or increased body fat, it is a totally unusual behavior compared to their usual eating pattern. The researchers attribute this change in behavior to greater activity of appetite-regulating genes activating at inopportune times.

Stafford Lightman, neuroscientist at the University of Bristol and author of the study, explains:

When we disrupt the normal relationship between corticosterone and the day-night light cycle, the result is abnormal regulation of genes and appetite during the period when animals normally sleep.

Rats with imbalanced corticosterone levels produced appetite-stimulating proteins at times when these genes are normally switched off. This phenomenon would lead to increased appetite during the night, according to the study.

Read more: When should you have your dinner? New research has the answer

How to minimize the impact of night work on health?

To minimize the impact of their working hours on their health, workers accustomed to night shifts can follow several recommendations, such as eating only during the day and limiting snacking or cravings in the middle of the night shift.

Restricted eating, which limits mealtimes but not necessarily calories consumed, may also help improve cardiovascular health, according to a three-month study of firefighters.

But as study co-author Becky Conway-Campbell, an endocrinology researcher at the University of Bristol, acknowledges, the brain signals that stimulate appetite can be 'difficult to neutralize by discipline or routine'.

In the future, research will continue in the pharmacological field, with the aim of designing products that could help reduce eating disorders. Becky Conway-Campbell concludes:

We hope that our results will also lead to a better understanding of how chronic stress and sleep disruption lead to caloric overconsumption.

Read more:This is why you should eat milk chocolate first thing in the morning

This article has been translated from Gentside FR.

Sources used:

Nature: Phase-shifting the circadian glucocorticoid profile induces disordered feeding behaviour by dysregulating hypothalamic neuropeptide gene expression

ScienceAlert: Phenomenon That Makes Night Shift Harmful to The Body Identified

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