The city of Tucson is replacing its street lighting this year with LED bulbs and will dim the lights at certain times.
"We're calling it a curfew," said Jessie Sanders who manages the LED project. Most of the city's lights will dim an additional 30 percent at midnight.
Meanwhile, the American Medical Association issued guidelines this month for cities to follow, warning that intense LED lighting disrupts sleep rhythms.
"What we've learned in the past few years is that some types of light stimulate the brain more than others," said Dr. Lois Krahn is a Mayo Clinic sleep expert.
