By Guest Author 27/08/2020

Recently, the Science Media Centre ran the first round of its 2020 SAVVY Video Competition for science researchers. With twelve entries, ranging from infant nutrition to the science of bell-ringing, we judges were incredibly impressed by the creativity and quality of submissions. This week, we’re featuring the work of runner-up prize winner, Dr Cherie Stayner.

Introducing the Diet, Rest, Eating and Activity Monitoring (DREAM) Study

A good night’s sleep is vital for health, wellbeing and behaviour in children, but research has shown that children who sleep less are at greater risk of obesity. How does not getting enough sleep lead to weight gain in children? The DREAM study hopes to answer this question.

The Edgar Diabetes and Obesity Research Centre (EDOR), housed in the University of Otago’s Department of Medicine, is investigating if changing the amount of sleep children get is linked to changes in their eating, exercise, or screen use. Children in the DREAM study (aged 8-12 years) are asked to go to bed one hour later than normal for one week, and then one hour earlier for another week. A number of interesting measures are assessed at the end of each week to see if there are any differences in children’s eating, movement and screen use behaviours when children are sleep deprived compared with well rested.

Do tired children just eat more?

Does staying up late simply allow for more opportunities to eat? Or do tired children eat differently than when they’ve had plenty of sleep – do they skip meals, eat more frequently or eat products that are higher in fat or sugar more often? To investigate these possibilities, the DREAM study uses standard methods for assessing dietary intake, supplemented with the use of wearable cameras which provide a novel way of directly measuring both food intake and eating behaviour – do children “sneak” food or snack more, for instance, during the week of mild sleep deprivation. At the end of each sleep intervention, children undertake a “feeding experiment” where they are treated to a buffet style main meal. When they are no longer hungry, they are offered a selection of desserts and other treats – not just for fun, but to allow us to objectively measure how much extra energy the tired versus well-slept children will eat, when they are already full.

Does less sleep correlate with changes in exercise?

On the other hand, maybe the link between sleep and obesity is because children who are tired do not have the same energy to be active as they would when they are well rested. The DREAM study is also measuring whether changes in physical activity occur in relation to sleep using a device called an actigraph (a bit like a FitBit). DREAM researchers analyse each child’s sequence of activities over a 24-hour period, such as moderate-to-vigorous physical activity (like running), light-intensity physical activity (like walking), sedentary behaviour (like reading), and sleeping. This allows researchers to look at the composition of movement over a 24-hour period, as time spent on one activity will have an impact on the time available for another activity.

Is the use of digital devices linked with sleep?

The wearable cameras provide careful measurement of screen use in children, which is also thought to be linked to sleep. Children wear a camera (that faces outwards) on their chest for four days during the two-week study period. The camera takes a photo every two seconds, which allows researchers to measure how much time children spend on digital devices, and to determine which types of devices they are using. The images can also reveal what the children are using the devices for. Are they playing games, watching movies or using social media websites? Additionally, the images taken from the camera will allow the social and environmental context of eating to be investigated. For instance, are children watching television or another digital device while they eat? Are they eating alone or with other people?

What will we discover through the DREAM study?

This study, involving more than 100 children and their families in the Otago region, will provide real insight into behaviours that could explain the strong link between insufficient sleep and excess body weight in children. Preliminary data have shown that children can successfully extend and reduce their sleep. Depending on the outcomes of the study, it is hoped that a sleep intervention could be one of the tools used in the future to combat obesity in children.

Watch Cherie’s prize-winning video entry here.