Sleep deprivation and drowsiness may have been a factor in some of the world's most notable disasters, including the fiery end to the Challenger space shuttle, Chernobyl [nuclear disaster] and the 1988 Exxon Valdez oil spill off the coast of Alaska. If you've ever pulled an all-nighter or been on a sleepless long-haul flight, you'll be familiar with the consequences-grogginess, grumpiness, reduced awareness and forgetfulness. In fact, just 17 hours of sustained wakefulness leads to a psychomotor deterioration equivalent to a blood alcohol level of up to 0.05 per cent.