Lasauskaite and Cajochen linked mental effort intensity and light color. The team “tested effort-related cardiac response under four lighting conditions and found that it decreased with color temperatures [i.e., as light got bluer]. Thus, blue-enriched light in offices and schools might . . . preserve resources during cognitive activities.”
Ruta Lasauskaite and Christian Cajochen. 2016. “Influence of Lighting Color Temperature on Mental Effort.” Psychology of Architecture Conference (December 4-5, Austin, TX) Program, p. 26.