With the flourishing of display technology nowadays, digital device makers tend to produce bright and vivid screen by using LED backlighting technology. However, you should be careful since this “eye-killer” can emit very strong blue light rays, which harm your eyes. In fact, studies have shown that prolonged exposure over time of blue light will cause digital eye strain, such as dry and irritated eyes. Although there are a large numbers of blue light filter apps (also known as Night Mode) that allow users to protect eyes, their efficiencies are still questioned. In this article, Allion argues that these apps can be useful tools for filtering out blue light. First, we will explain what blue light is. Then we will run tests after activating these apps.