Light generated outside of the natural cycle of the sun and moon can have unwanted effects, however, and is actually a form of pollution. Like other kinds, light pollution can harm animals, particularly nocturnal ones. Some predators which would otherwise turn in for the day are instead now choosing to hunt after dusk and disrupting entire food webs.

Artificial light at night can have particularly severe consequences for insects. For example, large numbers of moths distracted by the allure of street lighting were discovered to have been neglecting their nocturnal pollinating duties according to one study, with potentially severe consequences for the wider ecosystem.

How some insects are responding to the sudden brightening of their night-time habitat is still poorly understood. Common glow-worms (Lampyris noctiluca) are another nocturnal insect and they use bioluminescent signaling during mating. Female glow-worms stay put and use a chemical reaction to produce green bioluminescence in their abdomen, which attracts flying males.

Several field studies have shown that white light similar to that produced by modern LED street lighting can reduce the numbers of males that manage to find females. My research team and I wanted to find out what's going on, so we brought glow-worm mating into the lab.