Light is the primary signal that establishes the body’s circadian cycles. Exposure to bright light affects mood, attention, and activity levels. Findings from a recent study suggest that exposure to bright light reduces symptoms of hyperactivity in young children.

The study involved 48 preschool children (three to six years old) who were enrolled in E4Kids, a longitudinal study conducted in Australia. The children wore ActiGraph monitors (wristwatch-like electronic devices), which provided measurements of their light exposure and activity levels in one-minute intervals, for two weeks. Their parents provided information about the children’s sleep habits, activity levels, behavior, and demographics. The researchers collected other data about the children, including height, weight, body mass, activity/rest patterns, age, and gender.

They found that children who were exposed to brighter light for longer periods of time exhibited fewer symptoms of hyperactivity, regardless of the timing of the exposure. They noted these effects even at low levels of light, suggesting that young children are more sensitive to the effects of light than adults.

This was an observational study and did not identify mechanisms that drive the relationship between light exposure and behavior. However, the authors of the study posited that light exposure might influence norepinephrine release in the brain, promoting increased vigilance, alertness, and attention. They also suggested that light exposure promotes cortisol release, compensating for the diminished cortisol response commonly observed in children with attention disorders.

• Link to full study.