## Methods
### Experimental Setup  
The experiment was conducted in a soundproof room (3.6 m \(\times\) 3.6 m \(\times\) 4.1 m) with an off-white wall (90.12% reflectance) and ceiling (90.12% reflectance) and dark gray floor (18.88% reflectance). Four workstations were separated by partitions. In each workstation, there was a light gray desk (1.2 m \(\times\) 0.8 m, 50.77% reflectance) and one black chair. One white all-in-one computer (Lenovo C260, 19.5 in) with headphones, a keyboard and a mouse were placed on each desk. Moreover, in order to avoid the potential effect of natural light, no window was present in the room. The room temperature was kept at 26 \({}^{\circ}\)C by an air conditioner. For more details regarding the laboratory room, please refer to [PERSON] et al. (2019) [46], [PERSON] et al. (2018) [47] and [PERSON] et al. (2019) [48].  
Ambient illuminance levels (25, 50, 75 and 100 lx at eye level) were achieved by adjusting an intelligent desk LED lamp (Winstone-HSD9012A, Highstar) and were measured at eye level by a calibrated spectroradiometer (JETl Specbos1202, JETl Technische Instrumente GmbH, Jena, Germany) when the computer screen was turned off. The spectral power dis tributions of different illuminance conditions are displayed in Figure 2[49; 50]. Moreover, the spectrally weighted \(\alpha\)-opic illuminance levels and daylight equivalent illuminance (EDI) levels for each illuminance condition are listed in Table 1.  
One white all-in-one PC with a screen resolution of 1366 \(\times\) 768 pixels was used in the current study. Screen luminance levels were measured by a JETI Specbos1202 at a distance of 60 cm from the computer screen when a pure white picture was displayed on the screen in dark ambient conditions. We employed six levels of screen luminance in the current study: 3.87 cd/m\({}^{2}\) (10%), 21.47 cd/m\({}^{2}\) (20%), 42.74 cd/m\({}^{2}\) (40%), 64.12 cd/m\({}^{2}\) (60%), 84.77 cd/m\({}^{2}\) (80%) and 106.7 cd/m\({}^{2}\) (100%).  
The reading materials used in the formal laboratory study were six Chinese short novels. All reading materials selected in the current study were evaluated for likeability, understandability, and emotional arousal on a 5-point Likert scale by 10 other volunteers before the formal study. The results showed that the participants moderately liked the materials (\(M\) = 3.74, \(SD\) = 0.11), could understand the materials without difficulty (\(M\) = 3.12, \(SD\) = 0.05), and experienced slight affective arousal after reading the materials (\(M\) = 2.35, \(SD\) = 0.11). No significant difference in likeability (\(F\) (5, 24) = 0.23, \(p\) = 0.95), understandability (\(F\) (5, 24) = 0.35, \(p\) = 0.71), and emotional arousal (\(F\) (5, 24) = 0.12, \(p\) = 0.10) was revealed across the materials. Moreover, the reading materials were presented in black on a white background and uniformly arranged in 18-point Song font (character height was approximately 6 mm) with 1.5 times line spacing to maintain consistency.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & & \multicolumn{3}{c}{\(\alpha\)**-Opic lx [49]**} & \multicolumn{3}{c}{\(\alpha\)**-Opic EDI [51]**} \\ \hline  & **\(\Delta\)max (nm)** & **25 lx** & **50 lx** & **75 lx** & **100 lx** & **25 lx** & **50 lx** & **75 lx** & **100 lx** \\ \hline S-cone & 419.0 & 25 & 55 & 77 & 106 & 24 & 53 & 74 & 102 \\ Melanopsin & 480.0 & 22 & 46 & 65 & 86 & 20 & 42 & 58 & 78 \\ Rod & 496.3 & 23 & 49 & 68 & 91 & 21 & 44 & 62 & 83 \\ M-cone & 530.8 & 25 & 52 & 73 & 98 & 25 & 51 & 71 & 96 \\ L-cone & 558.4 & 25 & 51 & 72 & 96 & 25 & 52 & 74 & 99 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Spectrally weighted \(\alpha\)-opic illuminance levels and daylight equivalent illuminance (EDI) levels under 25, 50, 75 and 100 lx conditions.  
Figure 2: Spectral power distributions measured at eye level under 25, 50, 75 and 100 lx conditions.