One famous case is the disc jockey Peter Tripp who in 1959 stayed up for more than eight days as a promotional stunt. After a few days, he began to hallucinate, seeing kittens, mice, and cobwebs. He also became paranoid, insisting that an electrician had dropped a hot electrode into his shoe.

In 1964 high school student Randy Gardner (17) attempted to break the Guinness Book of World Records for the longest time awake -- 260 hours. And after 11 days without sleep he suffered no hallucinations or paranoia and no psychotic symptoms. But Coren challenges this often repeated fact in his book. Coren describes the day-by-day impact on Randy, as documented by John Ross of the US Navy Medical europsychiatric Research Unit in San Diego. Randy had trouble focusing his eyes on day 2, hallucinations on day 4, and slurred speech and a short attention span by the last day.

Certainly there are drugs such as caffeine, cocaine and amphetamines that keep you awake, but these cannot sustain you for very long.