Your office lights could be impacting your weight.

Image: iStock.

Well, it seems we’ve been undermining how much impact light, or lack thereof, has on our bodies.

Just last week, researchers discovered the amount of light exposure you get throughout the day plays a huge role in how well you sleep at night. However, a study released today suggests it’s not only the amount of light we encounter that affects us — it’s also the type of light.

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So here’s the bad news: it seems too much artificial light could be linked to increased body fat.

Which sucks if you’re one of the many thousands of Aussies who spend their day and overtime hours under the fluorescent lights of an office, or who work shift hours in artificial light while the rest of the world sleeps. (Post continues after gallery.)

But here’s the (sort of) good news: this has only been established in tests involving mice, not human beings. For the time being, anyway.

In the study, published in the Proceedings of the National Academy of Sciences, some mice were exposed to 16 or 24 hours of artificial light, while for comparison a control group was exposed to 12 hours of light and 12 of darkness.

After five weeks, the high exposure group had gained noticeably more body fat than the control group — 21 per cent more, to be precise — despite being fed the same food and sleeping for the same amount of time.

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According to the study’s co-leader Dr Patrick Rensen, the light exposure had affected the mice’s base metabolism, and more significantly, reduced the activity of their “brown fat”, also known as brown adipose tissue. During the test, the University of Leiden researchers had injected the mice with radioactively tagged fats to see how efficiently their bodies broke them down.

“As underlying mechanism we identified that brown fat, a tissue that combusts large amounts of fat into heat, becomes less active, resulting in reduced energy expenditure that leads to an increase in body fat,” he explained.

This could go some way in explaining why some humans store more fat than others, despite maintaining a healthy diet and lifestyle.

According to Healthline, the researchers speculate artificial light exposure effectively "tricks" an evolutionary function that allows the body to store fat during the sunny days of summer in preparation for the darkness of winter. Thus, being exposed to high levels of artificial light at night could confuse the body and make it alter its rate of fat burning.

Forbes reports the team is hoping to examine the impact of light exposure on the workings of 'brown fat' in the human body using student volunteers, who will sleep in the lab under different amounts of light and have their body fat monitored.

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“Modern 24-hour economy necessitates for work at night and shifts of social activities to the dark period. Our observations may implicate, assuming the data could be extrapolated to humans, that the current obesity epidemic is at least partly be due to increased light pollution and subsequent reduced brown fat activity,” the authors write.

Looks like this is one to watch.

How much artificial light is present in your day-to-day life?