Now here I go and add to your list of things to worry about. I have to admit that light pollution is not a physical danger to you. Mental maybe, but not physical. Well, that's not completely true, generating electricity by burning fossil fuels does contribute to air pollution, and most people can agree that air pollution is not healthy. We can all save money by the use of proper and efficient lighting.
Shielding can direct the light to where it is needed.
Shining all the light directly onto the desired place, allows you to use lower power bulbs without lowering the amount of light getting to where you want it. In many situations it might be practical to put a motion detector on the light, allowing the light to be on only when it is needed. Aside from making you drive up and down the Las Vegas strip slack jawed and wide eyed, it would have to be for safety and security. It's a waste of energy to shoot photons into the sky. Come on out to the George Observatory , and have someone show you the 'Houston Nebula'.