Study Compares The Effects Of Blue Light and Caffeine on Alertness and Cognitive Function

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A study by C. Martyn Beaven and John Ekstrom compared the effects of short wavelength light (blue light) and caffeine on human alertness and cognitive function.  During their experiment, the pair tested twenty-one healthy, non-athletic subjects (13 male and 8 female) to compare and contrast both the alerting effects and psychomotor effects of caffeine (240mg) and blue light (1-h dose of ~40 lx blue light) under four trial conditions.  The randomly assigned conditions included white light/placebo, blue light/placebo (blue light only), white light/240mg caffeine (caffeine only), and blue light/240mg caffeine (combined), with the conditions being introduced on different days.

The Effects Of Blue LightBefore the study, it had already been demonstrated that blue wavelength light enhances alertness and cognitive performance during daylight hours.  The study noted in its introduction that “the non-visual alerting effects of light have been shown to be mediated, at least in part, by a melanopsin-dependent photoreceptive system which is specifically sensitive to blue light (wavelengths of 460-480nm).”  The LED light chips in the Walalight System hit the exact range of nanometers that are suggested by the study’s authors to be effective.

Caffeine also has been shown to improve alertness, vigilance and mood.  However, exposure to blue light during the daytime has been reported to have a positive effect on subsequent sleep, in contrast to the negative effects on sleep that have been reported with caffeine.  This information indicated to the study organizers that although the effects of both blue light and caffeine might be comparable, they would be different under differing circumstances.

Results of the study showed that when it came to a visual reaction test requiring a decision, both the effects of blue light only and caffeine only conditions enhanced accuracy, while the fastest reaction times were seen with the combined blue light/caffeine condition, indicating that there was an additive effect when both conditions were introduced together.  When it came to a test of executive function that included a distraction, the blue light only condition consistently outperformed the caffeine only condition.  This occurred whether a congruent or incongruent distraction was introduced, with caffeine exerting a negative effect on accuracy when a distraction was included.  Visual reactions were also enhanced in the effects of blue light only condition in the absence of a distraction or decision, with the most prominent effects noticed in participants with blue eyes.

With results that consistently showed the positive effects of blue light on rapid decision-making, executive psychomotor function and visual reaction time, and showed improved effects in some scenarios over the administration of caffeine, Beaven and Ekstrom’s conclusion is that the alerting effect of blue wavelength light may have benefits in a variety of occupational contexts, including competitive sports scenarios.  Walalights emit the precise blue wavelength light deemed effective by the study’s authors, offering the same potential benefits as those discovered in the above-mentioned study.

The complete study titled “A Comparison of Blue Light and Caffeine Effects on Cognitive Function and Alertness in Humans” can be viewed below…