LED lights are the Olympic marathon runners among light bulbs: They use up to 90 percent less energy and last up to 25 times longer than conventional light bulbs. Scientists have found that the night sky has become nearly 10 percent brighter every year for the past decade because artificial lights, especially LEDs, emit too much glare.
The same outdoor lights also affect our health. They disrupt our circadian rhythms, reduce the effectiveness of our immune system and increase the incidence of certain diseases, including cancer. Authorities and organizations such as the National Park Service and the American Medical Association have made recommendations on how to reduce light pollution.