Robins are up all night singing because city lights convince them there is no end to the day, an expert has said.
Blue light from neon signs are likely to be especially disruptive to the robins' body clock, Dr David Dominone claims. As a result the birds' health could be suffering, he believes.
Speaking at the American Association for the Advancement of Science (AAAS) annual meeting, in San Jose, California, Dr Dominone said: "I live in Glasgow now and I hear robins singing throughout the night, singing all the time. Robins are one of the most sensitive species to light."
Dr Dominone, from the University of Glasgow, added: "This brings us to some of the physiological costs that that these environmental pressures might have. Words: PA
"Singing is a costly behaviour, it takes energy. So by increasing their song output, there might be some energetic costs."
Blackbirds are also badly affected by too much light, he said.
In Glasgow, noisy gulls were a known problem at night, especially during the breeding season between April and June.
Dr Dominone is putting cameras in nesting boxes to find out when robins sleep.
Laboratory tests had shown that light at night affected the activity of genes linked to the birds' body clock or "circadian" rhythms.
Several genes expressed at the wrong time of the day, including one involved in stress hormones. Dr Dominone said: "I think we should reduce the intensity of the light we put out, reduce the amount of light and try to think about the spectrum of the light we are putting out.
"In some cases, we can try to modify the street lamps, by putting shields on top to reduce light pollution."