White and Amber Light at Night Disrupt Sleep Physiology in Birds

• Published in: Current biology Vol. 30; no. 18; pp. 3657 - 3663.e5
• Main Authors: Aulsebrook, Anne E., Connelly, Farley, Johnsson, Robin D., Jones, Therésa M., Mulder, Raoul A., Hall, Michelle L., Vyssotski, Alexei L., Lesku, John A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 21-09-2020
• Subjects: anthropogenic; avian; blue light; circadian rhythms; electroencephalogram; light pollution; light spectra; sleep homeostasis; slow wave sleep; urbanization; light pollution; light spectra; slow wave sleep; anthropogenic; blue light; sleep homeostasis; circadian rhythms; urbanization; electroencephalogram; avian
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2020.06.085

Artificial light at night can disrupt sleep in humans [1–4] and other animals [5–10]. A key mechanism for light to affect sleep is via non-visual photoreceptors that are most sensitive to short-wavelength (blue) light [11]. To minimize effects of artificial light on sleep, many electronic devices shift from white (blue-rich) to amber (blue-reduced) light in the evening. Switching outdoor lighting from white to amber might also benefit wildlife [12]. However, whether these two colors of light affect sleep similarly in different animals remains poorly understood. Here we show, by measuring brain activity, that both white and amber lighting disrupt sleep in birds but that the magnitude of these effects differs between species. When experimentally exposed to light at night at intensities typical of urban areas, domestic pigeons (Columba livia) and wild-caught Australian magpies (Cracticus tibicen tyrannica) slept less, favored non-rapid eye movement (NREM) sleep over REM sleep, slept less intensely, and had more fragmented sleep compared to when lights were switched off. In pigeons, these disruptive effects on sleep were similar for white and amber lighting. For magpies, however, amber light had less impact on sleep. Our results demonstrate that amber lighting can minimize sleep disruption in some birds but that this benefit may not be universal.
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•Birds exposed to urban intensities of light at night have disrupted sleep•In pigeons, the impacts of white and amber light at night are very similar•In Australian magpies, sleep is more disrupted by white than amber light•The impacts of different types of lighting on sleep may be species specific
Aulsebrook, Connelly et al. show that birds exposed to urban intensities of artificial light at night sleep less, sleep less intensely, and have more fragmented sleep. For pigeons, white (blue-rich) and amber (blue-reduced) lighting have similar impacts. However, sleep in Australian magpies is more disrupted by white than amber light.