Light, Time of Day, May Be Risk Factor for Childhood Obesity

Could exposure to light, both artificial and natural, influence obesity in young children? A new Australian study suggest this could be a very real possibility as researchers discover light exposure plays a role in the weight of preschool children.

Researchers from Queensland University of Technology (QUT) followed children aged three to five, from six Brisbane childcare centers.

Ph.D. student Cassandra Pattinson and colleagues measured children’s sleep, activity and light exposure for a two-week period (Time 1), along with height and weight to calculate their BMI. They then followed up 12-months later to ascertain changes.

“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,” said Pattinson.

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 researchers accounted for Time 1 body weight, sleep, and activity.

“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.

“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 said 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 said.

“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 said 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 preschoolers and also infants,” she said.

“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.”

The study is published in the international research journal PLOS ONE.

Source: Queensland University of Technology
 
Obese child photo by shutterstock.