He's turned around the brand since then by reverting to the original customer-recognized color, blue.

FORBES: On The Cover/Top Stories

Lexus unveiled its LF-LC Concept last month in Sydney, since its blue opal color is inspired by the blue opal found in the Australian Outback, but this week in Los Angeles is the first time Americans will have a chance to see the 500-horsepower hybrid up close.

FORBES: At The LA Auto Show, Lexus Debuts A 500-Horsepower Hybrid

In two of the trials, the box was dark for 12 minutes and then illuminated for 48 minutes with either long-wavelength red light or short-wavelength blue light directed at the subjects' corneas. (Light color is determined by its wavelength.) The box was dark in a control experiment.

WSJ: The Secret to An Afternoon Energy Boost: Red Lighting