A Conversation with Charles A. Czeisler by Bronwyn Fryer:

At 12:30 am on June 10, 2002, Israel Lane Joubert and his family of seven set out for a long drive home following a family reunion in Beaumont, Texas. Joubert, who had hoped to reach home in faraway Fort Worth in time to get to work by 8 am, fell asleep at the wheel, plowing the family’s Chevy Suburban into the rear of a parked 18-wheeler. He survived, but his wife and five of his six children were killed.
The Joubert tragedy underscores a problem of epidemic proportions among workers who get too little sleep. In the past five years, driver fatigue has accounted for more than 1.35 million automobile accidents in the United States alone, according to the National Highway Traffic Safety Administration. The general effect of sleep deprivation on cognitive performance is well-known: Stay awake longer than 18 consecutive hours, and your reaction speed, short-term and long-term memory, ability to focus, decision-making capacity, math processing, cognitive speed, and spatial orientation all start to suffer. Cut sleep back to five or six hours a night for several days in a row, and the accumulated sleep deficit magnifies these negative effects. (Sleep deprivation is implicated in all kinds of physical maladies, too, from high blood pressure to obesity.)