Viola AU, James LM, Schlangen LJ, & Dijk DJ (2008). Blue-enriched white light in the workplace improves self-reported alertness, performance and sleep quality. Scandinavian journal of work, environment & health, 34 (4), 297-306 PMID: 18815716

Vandewalle, G., Maquet, P., & Dijk, D. (2009). Light as a modulator of cognitive brain function Trends in Cognitive Sciences, 13 (10), 429-438 DOI: 10.1016/j.tics.2009.07.004

Lehrl, S., Gerstmeyer, K., Jacob, J., Frieling, H., Henkel, A., Meyrer, R., Wiltfang, J., Kornhuber, J., & Bleich, S. (2007). Blue light improves cognitive performance Journal of Neural Transmission, 114 (4), 457-460 DOI: 10.1007/s00702-006-0621-4

Smith, A. (2002). Effects of caffeine on human behavior Food and Chemical Toxicology, 40 (9), 1243-1255 DOI: 10.1016/S0278-6915(02)00096-0