LED streetlights are coming to Philadelphia. Will they mess with our sleep?

Walk down a Philadelphia street at night and most likely, you will find the city lit in a warm yellow glow. The familiar cast comes from high-pressure sodium lights — the conventional breed of streetlamp common in the city. But soon, those yellow nights will be a memory. Instead, Philadelphia will take on a whitish cast as the city’s Streets Department moves forward with a long-anticipated plan to replace its old bulbs with more energy efficient LEDs. But as the city moves forward with the lighting makeover, experts are urging officials to consider public health and environmental questions raised by a 2016 study by the American Medical Association of the impact of LED lights.