An interesting article with some further information and discussion on the possible effects of light pollution on health and the environment:

---> How Light Pollution is Ruining Your Health - Articles

Organisms evolved to adjust themselves to predictable patterns of light and darkness. Once artificial light effectively varied the length of a day, something that happened less than a century ago, the average night's sleep decreased from around nine consistent hours to roughly seven, varying from one night to the next.

The irregularity prevents circadian rhythms from adjusting to a pattern, and creates a state of permanent "jet lag." This is true not only in humans but in many other species as well. IDA lists many of the far-reaching effects that light pollution has on the environment:

• Lighted towers and tall buildings confuse migrating and local birds, causing them to collide or circle the lights until they die of exhaustion.

• Sea turtle hatchlings are meant to crawl toward the ocean, guided by the light of the moon. Coastline lighting confuses them, drawing them away from the ocean instead of toward it.

• Glowworms and fireflies communicate through light, and artificial lighting makes this difficult.

• Intense lights for fishing at night attract large numbers of fish, leading to over-fishing and contributing to the decline of fish worldwide.

• Nighttime lighting from sports stadiums can stop the mating activity of nearby frogs.

So while electricity and efficient lighting have clearly provided major benefits to society, these benefits come with a price. A sensible solution, as IDA suggests, is to use outdoor light at night only when and where it is needed and at appropriate lighting levels. They also suggest using fully shielded, light-efficient fixtures aimed directly at the ground, and incorporating timers and sensors to shut off lights when they’re not needed.

Related: Is Light Pollution an Important Environmental Issue?