What is the longest time a person has ever stayed awake?

The record for the longest period without sleep is 18 days, 21 hours, 40 minutes during a rocking chair marathon. The record holder reported hallucinations, paranoia, blurred vision, slurred speech and memory and concentration lapses. (From National Sleep Research, 40 Amazing Facts About Sleep, http://www.abc.net.au/science/sleep/facts.htm)

There are stories about people going even longer without sleep. A man in Vietnam supposedly has gone 33 years without sleep (http://www.thanhniennews.com/features/?catid=10&newsid=12673).