Do urban fish exhibit impaired sleep?

Melatonin controls the body clock — high melatonin levels make us feel tired in the evening. However, the hormone also plays an important role in animals’ biological rhythms. Artificial light at night — light pollution — can suppress the production of melatonin in fish, even at very low light intensities, a finding established by researchers from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB).
Go to Source