Children exposed to both artificial and natural light at higher risk of obesity

Children aged three to five were found to significantly gain weight when exposed to both natural and artificial light within 12 months. A new Australian study shows exposure to light could lead to obesity in young children, supporting earlier studies that suggest timing and intensity of light exposure is critical for metabolic functioning and weight status in mammals.

The study, published in the journal PLOS ONE, suggests that light can now be “added to the mix” of the factors that contribute to obesity, such as calorie intake, poor physical activity, short sleep duration and variable sleep timing.

Researchers from Queensland University of Technology (QUT) said that timing, intensity and duration of exposure to artificial and natural light deliver acute biological impacts in mammals. Light exposure affects the circadian clock, or the internal body clock, which could alter sleep patterns, cause weight gain or loss, and lead to hormonal and mood changes.

In the study, researchers have found moderate intensity light exposure earlier in the day contributed to the increased body mass index (BMI) of children after two weeks. However, children who were greatly exposed to outdoor and indoor light in the afternoon were found to be slimmer.

The researchers followed the children for another 12 months and they found that children who received more light in the first two weeks of the study had higher body mass. Even considering their body weight, sleep and activity, light delivered a significant impact on their weight, researchers say.

The findings come from the analysis of the health of children aged three to five from six Brisbane childcare centres. The researchers examined the sleep, activity and light exposure of the children along with their height and weight.

“Around 42 million children around the globe under the age of five are classified as overweight or obese so this is a significant breakthrough and a world-first,” said researcher Cassandra Pattinson, a Ph.D. student at QUT. “This research suggests that exposure to different types of light (both artificial and natural) at different times now needs to be part of the conversation about the weight of children.”

“This increase in light exposure has paralleled global increases in obesity,” she added. The researchers are planning to conduct further studies with pre-schoolers and infants to determine how the findings can be used to fight obesity in children.