Courtneyk/Getty Images The message is across: blue light is bad for your health. Where is it? Experts will tell you: blue light at night can reduce the quality of your sleep. That’s part of why the blue light-blocking glasses industry could reach $5 billion over the next decade. But experts also say that blue light is good for you and that your phone may be keeping you up at night for reasons other than light exposure. The sun is the main source of blue light. Humans are programmed to wake…