When we returned from vacation at the end of July, the LED street lights we found in our Auburndale neighborhood were a huge disappointment. The new LED bulbs emit an extremely harsh, glaring bluish light that intrudes into our house. The lighting that reaches the ground seems several times brighter than the old street lamps, much brighter than is needed at night. The glare washes out the sky. When I went outside on a night with a few clouds, I could see only a handful of stars and the moon looked dim in comparison with the glaring streetlights.
….This is not just a problem of appearance. The body’s daily rhythm of alertness and rest depend on receptors in the eye that respond to blue light. As the sun rises higher in the sky, the fraction of blue light increases and we become more alert; as the sun sinks low, the fraction of blue light drops and we get ready for sleep. Too much blue light at the wrong time can disrupt some people’s sleeps. Animals have a similar sensory response, so bright bluish streetlights will disrupt their diurnal rhythms. Bright night lighting can also affect plants.