Blue light filter cares for your eyes and support you sleep efficiently. What is Bluelight? Blue light is visible light, including computers, cell phones, televisions and lights. During the day, natural exposure to blue light can enhance people's energy, alertness and passions. However, prolonged exposure of waves propagating through the screen device during night time in a dim environment can disrupt the circadian rhythm and cause various health effects, including interruptions in the normal sleep schedule. Blue screen at night time is harmful. Therefore, blue light should be reduced at night. Night filter is necessary. Features • Reduces the blue light • Adjusts density of filter • Saves battery • Using easy and fast