Welch said reducing light pollution had benefits for health, nocturnal ecology and enjoyment of the night sky.

"Dark" sleep aided the body's ability to fight disease, while excessive light adversely affected animal habitats.

"Light can distract and kill in a very direct sense. For example, birds flying into buildings and interference with reproduction behaviour," he said. "In some species we do know that mating behaviour is suppressed when it's not truly dark."

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