The nighttime environment is a precious natural resource for all life on Earth, which exists in a rhythm of light and dark provided by the sun, moon and stars, quietly guiding all living things since life began. Now, artificial lights overpower the darkness and our cities glow at night, disrupting the natural day-night pattern and shifting the delicate balance of our environment. The glow of excessive outdoor lighting has hidden the stars and changed our perception of the night.
Source: Do we really need night lighting? – Wilmington News Journal
The Urban Night 