Current Biology
Volume 30, Issue 18, 21 September 2020, Pages 3657-3663.e5
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White and Amber Light at Night Disrupt Sleep Physiology in Birds

https://doi.org/10.1016/j.cub.2020.06.085Get rights and content
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Highlights

  • 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

Summary

Artificial light at night can disrupt sleep in humans [1, 2, 3, 4] and other animals [5, 6, 7, 8, 9, 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.

Keywords

anthropogenic
avian
blue light
circadian rhythms
electroencephalogram
light pollution
light spectra
sleep homeostasis
slow wave sleep
urbanization

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6

These authors contributed equally

7

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