This is a big one, which most people don’t even realize harms their sleep and productivity. Short-wavelength blue light plays an important role in determining your mood, energy level, and sleep quality. In the morning, sunlight contains high concentrations of this blue light. In the afternoon, the sun’s rays lose their blue light, which allows your body to produce melatonin and this starts making you sleepy.
By the evening, your brain doesn’t expect any blue light exposure and is very sensitive to it. Most of our favorite evening devices—laptops, tablets, and mobile phones—emit short-wavelength blue light brightly and right in your face.
As we’ve all experienced, poor nights’ sleep has disastrous effects. The best thing you can do is to avoid these devices after dinner (television is OK for most people, as long as they sit far enough away from the set).