Short exposure to blue light helps in faster decision making: study

Spending half an hour in blue light may help you make difficult decisions faster up to 40 minutes after the exposure has ended, a new study suggests. Researchers from University of Arizona in the US found that blue wavelength light exposure led to subsequent increases in brain activity in the dorsolateral prefrontal cortex (DLPFC) and the ventrolateral prefrontal cortex (VLPFC) when participants were engaging in a cognitive task after cessation of light exposure.

The results also showed that a short single exposure to blue light for half an hour is sufficient to produce measurable changes in reaction times and more efficient responses (answered more items correctly per second) during conditions of greater cognitive load after the light exposure had ended. Moreover, 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,” said Anna Alkozei from University of Arizona.

“Blue-enriched white light could be used in a variety of occupational settings where alertness and quick decision making are important, such as pilot cockpits, operation rooms, or military settings. It could also be used in settings where natural sunlight does not exist, such as the International Space Station,” said Alkozei.

“Importantly, our findings suggest that using blue light before having to engage in important cognitive processes may still impact cognitive functioning for over half an hour after the exposure period ended,” she added.

According to Alkozei, this may be valuable in a wide range of situations where acute blue light exposure is not a feasible option, such as testing situations. The study consisted of 35 healthy adults between the ages of 18 and 32 years.

Participants were randomised 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).

“These findings are important as they link the acute behavioural effects of blue light to enhanced activation of key cortical systems involved in cognition and mental control,” said William D S Killgore from University of Arizona. The findings were published in the journal Sleep.