Sleep is said to be the greatest mystery in neuroscience. However, scientists are coming to gradually understand the mystery of sleep thanks to the discovery of a substance called orexin. Next generation sleeping medications are being developed using that mechanism. Dr. Masashi Yanagisawa of the University of Tsukuba, the researcher who discovered orexin, sought out mice with abnormal sleep patterns and is now searching for a genetic cause. We'll look at the latest research concerning sleep.