“Light pollution,” simply put, is light that is going where it’s not wanted. While light pollution is a topic near and dear to the hearts of astronomers, as a reality it is something that affects everyone and everything with varying degrees of seriousness, from disrupted sleep to confused wildlife to cancer.
As you consider placing lights, please consider the following:
Light pollution has been linked to sleep disorders (Missing the Dark: Health Effect of Light Pollution)
Light pollution negatively affects sea turtles, birds, and other wildlife
Light pollution has been linked to breast cancer (Light at Night and Breast Cancer Risk Worldwide)
Light pollution is a manifestation of wasted energy
Light pollution washes out the night sky, blotting out all but the very brightest stars
More light pollution studies are still being added to the library yearly.
We aren’t trying to suggest that all lighting is bad or unnecessary. Light is required for nighttime work and safety. However, there is good lighting and bad lighting. Good lighting should be well planned for optimum placement and well shielded for optimum efficiency. Everyone and everything can benefit from well shielded and planned lighting.
Global sources for your consideration:
Local references (at least within Indiana):