Different artificial light modalities during daytime have all positive effects on attention and alertness

Light exposure during the day exerts acute effects on attention, such as how alert and ready a person is for solving problems and goal-oriented behavior. However, to increase the understanding of how different light modalities during daytime affect our attention, there is a need for more studies. The current study tested the acute effects of daytime exposure to four artificial light modalities on attention and alertness with the Psychomotor Vigilance Task (PVT). Healthy, young adults (N = 39; mean age: 21.7, 61.5% females) performed the PVT three times in four light modalities presented on separate days at the same time-of-day (09:00-11:00): short-wavelength light [SWL, 'blue'], long-wavelength light [LWL, 'red'], bright white light [BWL], and dim light [DL] as control. Attention and alertness measures included fluctuations in attention, quantified as the number of lapses and Reaction Time (RT) variability, mean RT, and optimum response capability (10% fastest RTs). Compared to DL, participants had significantly fewer lapses and faster mean RT during all three light conditions and enhanced optimum response capability during SWL and LWL. Light did not appear to have effects on intra-individual RT variability. Results suggest that 2 hours of exposure to artificial light during daytime can induce alerting effects and fewer attentional lapses in young, healthy adults. Surprisingly, neither SWL, LWL, nor BWL were significantly superior to one another.