His Holiness the Dalai Lama’s second day of dialogue with scientists in Tokyo

Tokyo, Japan, 7 November 2012 – The second day of His Holiness’ first major, multi-day discussion on science in Japan began with Dr. Masashi Yanagisawa, of Tsukuba University, delivering a talk on “The Mystery of Sleep and Waking.” Sleep, the professor pointed out, is only a time for the brain to rest; but the electricity in the brain is not turned off during sleep. It’s just set on “maintenance mode,” as it were. The amount of sleep each animal needs varies greatly—from 4 hours a day for sheep to 17 hours for hedgehogs—but there’s no species that does not require sleep.
fonte dalailama.com