Can nights ever vanish?

We need darknes. A National Geographic essay talked about how many countries and many cities in the world have started to kill the line between night and day so that “most city skies have become virtually empty of stars.”
We are diurnal animals, meaning that our eyes are built to receive the light of the sun. For us, therefore, as it is differently to the nocturnal ones, the difference between light and darkness is not simply a moral binary but a physical element in our life. What happens when night is as bright as day?