DOI: 10.5061/dryad.dr8277c
title: Data from: The preference and costs of sleeping under light at night in forest and urban great tits

description: Artificial light at night (ALAN) is an increasing phenomenon associated
 with worldwide urbanisation. 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 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 naïve birds that never encountered light at night, white
 light might disrupt circadian rhythms more than green light. However, it
 is possible that 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.
description: Choice experiment -
 Figure 1Dataset used for the
 analysis of experiment 1 (choice experiment). Results are shown in figure
 1.choice -
 Figure 1.xlsxProportion of movements
 at night - Figure 2aDataset used for the
 analysis of the proportion of movement (nocturnal restlessness) of birds
 at night. Results shown in Figure 2a.sleepmovement - Figure
 2a.xlsxDelta oxalic acid -
 Figure 2bDatast used for the
 analyis of changes in plasma oxalic acid levels. Results shown in figure
 2b.DeltaOA
 - Figure 2b.xlsxCognitive tests - Figure
 2cDataset used for the
 analysis of the cognitive tests. Results shown in figure
 2c.cognition - Figure
 2c.xlsxDEE - Figure
 2dDataset used for the
 analysis of daily energy expenditure (DEE). Results shown in figure
 2d.onset-offset of activity
 - Figure S2abDataset used to analyse
 the onset and offset of daily activity. Results are shown in supplementary
 figure 1 (panels a and b).onset&offset - Figure
 S2ab.xlsxnight and total activity
 - Figure S2cdDataset used to analysed
 nocturnal and total daily activity. Results are shown in supplementary
 figure 2 (panels c and d).night&total - Figure
 S2cd.xlsx