Your smartphone addiction isn't helping you sleep. In fact, an obscure chemical reaction may be keeping you awake. The latest Reactions video looks at the process that connects your late-night texts to your lack of sleep. Your smartphone, tablet and other devices emit large quantities of blue light wavelengths. This tells your body "wake up!" when you should be getting ready to sleep. Your body gets that signal through melanopsin, a protein that hangs out behind your eye and undergoes a chemical change that in turn signals your body's master clock. So turn off the phone long before you go to bed. It'll be there in the morning. Thanks to Brian Zoltowski of Southern Methodist University.