Short answer is because human eyes don’t respond well to the color red, so it’s a very poor color choice for illumination purposes. Longer answer is the whole idea of having lights at night is to be able to see things at night. Human eyes are more sensitive to green and yellow, less sensitive to blue and red.

Why is it bad to have red LED lights on at night?

The theory is that red light wavelengths stimulate the production of melatonin. Melatonin is a naturally occurring hormone that helps you sleep. Your brain releases more melatonin as darkness falls and tends to release less when you’re exposed to light.

Is red LED light harmful?

Red light therapy is considered safe and painless. However, there have been reports of burns and blistering from using RLT units. A few people developed burns after falling asleep with the unit in place, while others experienced burns due to broken wires or device corrosion.