LED light bulbs are the future. They're better for the environment and the pocket book. But for some people, certain LEDs lights — particularly holiday lights—are also a problem. They flicker in a way that causes headaches, nausea and other discomfort. Today, we visit the "Flicker Queen" to learn why LEDs flicker — and what you can do about it.Wondering about other quirks of lighting and engineering? Email us at shortwave@npr.org – we might cover it on a future episode!