Everyday environmental light exposure and 24-hour activity in children

Background: Light is an important physiological input into children’s health and wellbeing, with a particular role in the timing of their circadian activity and sleep-wake processes. Increased use of artificial lighting suggests a broader range in the timing, intensity, spectra, and duration of everyday light exposure. However, the consequences of this exposure for children are not well understood.

Purpose: The potential impacts of light from digital devices, specifically on children’s sleep and 24-hour activity, is controversial. In this study we explored the habitual light environments experienced by children.

Methods: This feasibility and acceptability study included children aged 5- 8 years. Children wore a novel digital spectrometer on their chests during the day, and on their bedside during the night, together with an actigraph for 48-hours. Their carers completed a time-use diary (including physical and digital activities). The study examined the feasibility of this new form of ‘wearable’ via a brief evaluation interview with the children.

Results: 20 children were recruited into the study (12 boys, 8 girls). Feasibility testing supported high acceptability and adherence to the study protocol. Well defined 24-hour spectral profiles (340-1010nm) were determined for each child. The light profiles were characterized with respect to estimated non-visual photoreception and circadian responses, in parallel with 24-hour activity and sleep-wake estimates.

Conclusions: This study presents data that supports the feasibility of novel light exposure metrics. Understanding the impact of increased use of digital devices by children, the control of their light environments, and the interactions between light and activity requires new measures and protocols.

Practical implications: These new tools are well accepted by children and provide unique data that will help improve understanding of the effects of light on children’s 24-hour activity and health.

Funding: This project was supported by the ARC Centre of Excellence for the Digital Child (CE200100022).