Researchers from the University of Auckland are calling for more research on the effects of light and noise pollutions on birds' sleeping patterns, and the knock-on effects of sleep deprivation on their vocal communication.

Authors of the paper published in the online journal of Biology Letters, said there are good reasons to predict that sleep deprivation could affect song-learning and memory, mating, and territorial behavior, with important implications for bird conservation in urban areas worldwide.

Sleep is found in every animal studied to date, from jellyfish and flatworms to birds and mammals. In humans, sleep deprivation affects speech and language learning.