A study conducted by researchers at the University of Arizona (Tucson, AZ) found that blue light exposure led to subsequent increases in brain activity in two areas of the prefrontal cortex when participants were engaging in a cognitive task after cessation of light exposure.
The study, which consisted of 35 healthy adults between the ages of 18 and 32, were randomized to receive a 30-minute exposure to either blue (active) or amber (placebo) light immediately followed by a working memory task during functional magnetic resonance imaging (fMRI). The results showed that a short single exposure to blue light for 30 minutes is sufficient to produce measurable changes in reaction times and more efficient responses during conditions of greater cognitive load after the light exposure had ended. These improvements were directly associated with measurable changes in the activation of the prefrontal cortex.
"Previous studies only focused on the effects of light during the period of exposure. Our study adds to this research by showing that these beneficial effects of blue wavelength light may outlast the exposure period by over 40 minutes," says lead author Anna Alkozei, Ph.D., a postdoctoral fellow in the Department of Psychiatry at the University of Arizona. Blue-enriched white light, Alkozei explains, could be used in occupational settings where alertness and quick decision-making are important, such as pilot cockpits, operating rooms, or military settings, as well as in settings where natural sunlight does not exist.
Alkozei and her team's findings suggest that using blue light before having to engage in important cognitive processes may still impact cognitive functioning for over 30 minutes after the exposure period ended, which could be useful in situations where acute blue light exposure is not a feasible option, such as testing situations, she says.
Full details of the work were presented at the SLEEP 2016 annual meeting, held June 11-15 in Denver, CO (abstract title: "Exposure to blue wavelength light is associated with increased dorsolateral prefrontal cortex responses, and increases in response times during a working memory task"); for more information, please visit www.sleepmeeting.org.