A Queensland University of Technology (QUT) study revealing light exposure plays a role in the weight of preschool children has been published by PLOS ONE.

PhD student Cassandra Pattinson and colleagues Simon Smith, Alicia Allan, Sally Staton, and Karen Thorpe studied children aged 3 to 5, from six Brisbane childcare centers. At time 1, they measured children’s sleep, activity and light exposure for a two week period, along with height and weight to calculate their BMI, then followed up 12-months later.

“At time 1, we found moderate intensity light exposure earlier in the day was associated with increased body mass index (BMI) while children who received their biggest dose of light—outdoors and indoors—in the afternoon were slimmer,” says Pattinson in a release. “At follow-up, children who had more total light exposure at Time 1 had higher body mass 12 months later. Light had a significant impact on weight even after we accounted for Time 1 body weight, sleep, and activity.

“Around 42 million children around the globe under the age of 5 are classified as overweight or obese, so this is a significant breakthrough and a world-first.

“Artificial lighting, including light given off by tablets, mobile phones, night lights, and television, means modern children are exposed to more environmental light than any previous generation. This increase in light exposure has paralleled global increases in obesity.”

The research team is from QUT’s Institute of Health and Biomedical Innovation and the Centre for Children’s Health Research.
Pattinson says it is known the timing, intensity, and duration of exposure to both artificial and natural light have acute biological effects in mammals. “The circadian clock—also known as the internal body clock—is largely driven by our exposure to light and the timing of when that happens. It impacts on sleep patterns, weight gain or loss, hormonal changes, and our mood,” Pattinson says. “Factors that impact on obesity include calorie intake, decreased physical activity, short sleep duration, and variable sleep timing. Now light can be added to the mix.”

Pattinson says the next step was to figure out how the research can be used in the fight against obesity in children. “We plan to conduct further studies with pre-schoolers and also infants,” she says. “Animal studies have shown that timing and intensity of light exposure is critical for metabolic functioning and weight status. Our findings suggest that the same applies to us.

“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.”

QUT is part of a national collaborative group of five major Australian universities that form the ATN (Australian Technology Network of Universities).