“Screens, including TVs, computers, tablets, iPhones and video games, can emit a blue light that can be a strong signal to your brain that it’s daytime or wake time. If the screen is being used at night, it can send your body a signal that makes it difficult to know it’s nighttime and sleep time. That can make it harder to go to sleep and stay asleep,” says CHOC pediatric neurologist Dr. Anjalee Galion.