From David M. Friedman’s The Immortalists: Charles Lindbergh, Dr. Alexis Carrel, and Their Daring Quest to Live Forever:

The initial stages of these studies were performed in Carrel’s operating suite, which the two men now entered. Lindbergh had never been in an operating room before, and this one defied his expectations. The floor, walls, and ceiling were painted black. The only source of illumination was a large skylight situated directly above the operating table, which was black as well, as were all the storage cases and cabinets in the room.

“Too much light inhibits the activity of the brain,” Carrel said, anticipating Lindbergh’s question. “Surely you’ve noticed that the world’s great civilizations have formed far above the equator, where there is much less direct sunlight than in tropical regions.”

Carrel told Lindbergh that black walls cut down on glare–no small worry when one is operating on tiny blood vessels. He also said that black surgical gowns were better than traditional white ones at illuminating dust, the elimination of which was an obsession for Carrel, who insisted on the highest standards of sterility and cleanliness in his operating rooms.