'LED street lights are disturbing my sleep'

In towns and cities across the world, the colour of night is changing. Traditional yellow sodium street lights are steadily being replaced by white LED bulbs. The new lights use less energy, dramatically cutting carbon emissions and saving money. But not everybody is happy.  "When the leaves left the trees and I tried to sleep, I turned to one side and the light's shining right in my eyes." Like most of us, Karen Snyder had never really paid much attention to street lights. But that all changed last year when the city council began installing LED lights outside her home in a quiet corner of Washington DC.