Night Swannies block around 80% of green light. We are primarily focused on blocking blue light as the research supports this being the far more important wavelength to block for both sleep and eye protection. The effectiveness has been proven in independent studies which you can read about at the following link: swannies.com/science.
Recent research actually indicates that there is likely to be little added benefit to blocking 100% of green light and there are actually possible downsides to doing so. You can read more extensively about these studies in our research article: Green Light: The Facts.
The studies also categorically indicate that when compared to green light, blue light is more effective at increasing alertness, performance, brain activity and impacting sleepiness. This is why we believe it is more important to focus on blocking blue light, which also results in a better visual experience for the wearer, as blocking more green light requires a darker red lens which most people find unpleasant or unusable.
We recommend being cautious with any source that suggests that blocking green light is just as important, because this does not have scientific basis.