by Julie Fidler, Natural Society:
LED street lights are so hazardous to people’s health that the American Medical Association (AMA) has adopted an official policy about them.
Adopted unanimously at the AMA’s annual meeting in Chicago on June 14, 2016, the policy comes in response to the growing number of LED street lights in the country. An association committee issued guidelines on how communities can choose LED streetlights “to minimize potential harmful human health and environmental effects.”
Long-lasting LED lights are quickly replacing existing streetlights because they save municipalities money on energy and maintenance. But the AMA’s stance reflects the importance of properly designing new technologies and the tight link between light and human health.
In the statement, the AMA recommends that outdoor lighting at night, especially street lights, should have a color temperature (CT) no greater than 3,000 Kelvin (K). A light’s CT is a measure of the spectral content of light from a source – how much blue, green, yellow, and red there is in it. A higher CT rating usually means a light contains more blue content, which makes the light appear whiter. 
Bright LED street lights have been shown to make people feel safer. They also make it easier for police to distinguish the colors of the cars they are chasing. 
This Lights Comes with Risk
But blue light has a dark side. Research suggests that blue light can prevent people from sleeping, or make them sleep poorly, because it throws off the body’s circadian rhythm. This is one of the problems the AMA sites in its statement.