A1 Journal article (refereed)
The preference and costs of sleeping under light at night in forest and urban great tits (2019)

Ulgezen, Z. N., Käpylä, T., Meerlo, P., Spoelstra, K., Visser, M. E., & Dominoni, D. M. (2019). The preference and costs of sleeping under light at night in forest and urban great tits. Proceedings of the Royal Society B : Biological Sciences, 286(1905), Article 20190872. https://doi.org/10.1098/rspb.2019.0872

JYU authors or editors

Publication details

All authors or editors: Ulgezen, Zeynep N.; Käpylä, Teemu; Meerlo, Peter; Spoelstra, Kamiel; Visser, Marcel E.; Dominoni, Davide M.

Journal or series: Proceedings of the Royal Society B : Biological Sciences

ISSN: 0962-8452

eISSN: 1471-2954

Publication year: 2019

Volume: 286

Issue number: 1905

Article number: 20190872

Publisher: Royal Society

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1098/rspb.2019.0872

Publication open access: Not open

Publication channel open access: 

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/66129

Abstract

Artificial light at night (ALAN) is an increasing phenomenon associated with worldwide urbanization. In birds, broad-spectrum white ALAN can have disruptive effects on activity patterns, metabolism, stress response and immune function. There has been growing research on whether the use of alternative light spectra can reduce these negative effects, but surprisingly, there has been no study to determine which light spectrum birds prefer. To test such a preference, we gave urban and forest great tits (Parus major) the choice where to roost using pairwise combinations of darkness, white light or green dim light at night (1.5 lux). Birds preferred to sleep under artificial light instead of darkness, and green was preferred over white light. In a subsequent experiment, we investigated the consequence of sleeping under a particular light condition, and measured birds' daily activity levels, daily energy expenditure (DEE), oxalic acid as a biomarker for sleep debt and cognitive abilities. White light affected activity patterns more than green light. Moreover, there was an origin-dependent response to spectral composition: in urban birds, the total daily activity and night activity did not differ between white and green light, while forest birds were more active under white than green light. We also found that individuals who slept under white and green light had higher DEE. However, there were no differences in oxalic acid levels or cognitive abilities between light treatments. Thus, we argue that in naive birds that had never encountered light at night, white light might disrupt circadian rhythms more than green light. However, it is possible that the negative effects of ALAN on sleep and cognition might be observed only under intensities higher than 1.5 lux. These results suggest that reducing the intensity of light pollution as well as tuning the spectrum towards long wavelengths may considerably reduce its impact.

Keywords: circadian rhythm; light pollution; urbanisation; sleep; energy consumption (metabolism); great tit

Free keywords: Parus major; artificial light at night; light pollution; oxalic acid; sleep; urbanization

Contributing organizations

Ministry reporting: Yes

Reporting Year: 2019

JUFO rating: 3