late 15th cent. (as an adjective in the sense 'demented'): from French dément or Latin demens, dement- 'insane'. The noun use dates from the late 19th cent
That means sleeplessness is of “epidemic proportions in this country,” says Dr. William Dement, director of the Sleep Disorders Center at Standford University School of Medicine. 斯坦福大学医学院睡眠失调中心主任威廉·迪蒙特说，这意味着睡眠不足“在这个国家里已经到了流行病的地步”。
