In a recent post, we explored the negative effects of blue light on sleep, but while those effects may be hazardous for sleep, they can be quite beneficial when we’re awake.
Blue Light improves alertness and cognitive function
If you’re reliant on your morning cuppa to kick start the old “grey cells”, you may want to reconsider using blue light instead… In a study comparing the effects of blue light versus caffeine on cognitive function and alertness, researchers found that while both blue light and caffeine had beneficial effects, subjects who received blue light only consistently out-performed the caffeine subjects. This is likely due to the negative effects of caffeine on anxiety, whereas blue light has none.
A comparison of blue light and caffeine effects on cognitive function and alertness in humans – PLoS One, 2013
Twenty-one healthy subjects performed a computer-based psychomotor vigilance test before and after each of four randomly assigned trial conditions performed on different days: white light/placebo; white light/240 mg caffeine; blue light/placebo; blue light/240 mg caffeine. Both the caffeine only and blue light only conditions enhanced accuracy in a visual reaction test requiring a decision and an additive effect was observed with respect to the fastest reaction times. However, in a test of executive function, where a distraction was included, caffeine exerted a negative effect on accuracy. Furthermore, the blue light only condition consistently outperformed caffeine when both congruent and incongruent distractions were presented. The visual reactions in the absence of a decision or distraction were also enhanced in the blue light only condition and this effect was most prominent in the blue-eyed participants.
In another study, researchers found that the use of “blue-enriched” white light in a classroom helped to improve the students’ concentration and increase their cognitive processing speed.
Influence of blue-enriched classroom lighting on students’ cognitive performance – Trends in Neuroscience and Education, 2014
58 High school students were recruited from four classes in two schools. In each school, one classroom was equipped with blue-enriched white lighting while the classroom next door served as a control setting. The effects of classroom lighting on cognitive performance were assessed using standardized psychological tests. Results show beneficial effects of blue-enriched white light on students’ performance. In comparison to standard lighting conditions, students showed faster cognitive processing speed and better concentration. The blue-enriched white lighting seems to influence very basic information processing primarily, as no effects on short-term encoding and retrieval of memories were found.
In Psychology Today, they reported that across all measures, extended exposure to blue light significantly increased alertness. Compared to green light exposure, blue light exposure:
- decreases sleepiness
- increases reaction times
- increases levels of alertness
- increases attention span in performance tests
- alters brain activity indicating heightened alertness
In addition to increased alertness and reduced sleepiness, exposure to blue light during the daytime may actually improve sleep at bedtime. So perhaps the best approach might be: blue light during the day but none after dark? Something to try…