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Streetlights disrupt night-time sleep in urban black swans

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posted on 2022-03-30, 05:05 authored by Anne AulsebrookAnne Aulsebrook, John LeskuJohn Lesku, RA Mulder, W Goymann, AL Vyssotski, TM Jones
Artificial light at night could have widespread and detrimental impacts on sleep. To reduce disruptive effects of artificial light on sleep in humans, most smartphones and computers now have software that reduces blue light emissions at night. Little is known about whether reducing blue light emissions from city lights could also benefit urban wildlife. We investigated the effects of blue-rich (white) and blue-reduced (amber) LED streetlights on accelerometry-defined rest, electrophysiologically-identified sleep, and plasma melatonin in a diurnal bird, the black swan (Cygnus atratus). Urban swans were exposed to 20 full nights of each lighting type in an outdoor, naturalistic environment. Contrary to our predictions, we found that night-time rest was similar during exposure to amber and white lights but decreased under amber lights compared with dark conditions. By recording brain activity in a subset of swans, we also demonstrated that resting birds were almost always asleep, so amber light also reduced sleep at night. We found no effect of light treatment on total (24 h) daily rest or plasma melatonin. Our study provides the first electrophysiologically-verified evidence for effects of streetlights on sleep in an urban animal, and furthermore suggests that reducing blue wavelengths of light might not mitigate these effects.


This research was funded by the Hermon Slade Foundation (awarded to TJ), Australian Research Council (DP170101003 awarded to JL), HolsworthWildlife Research Endowment (Equity Trustees Charitable Foundation & the Ecological Society of Australia awarded to AA), Australasian Society for the Study of Animal Behaviour (awarded to AA), and BirdLife Australia (awarded to AA).


Publication Date



Frontiers in Ecology and Evolution



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Frontiers Media



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© 2020 Aulsebrook, Lesku, Mulder, Goymann, Vyssotski and Jones. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.