Tony Wright was tired, and with good reason. He'd been awake for 11 days, two hours -- a world record.
"I tend to feel better in my body when I've been awake 4, 5, 6 days," he said.
Wright, a 43-year-old gardener from Cornwall, England, thinks sleep deprivation might open a world of enhanced brain function. Most sleep researchers strongly disagree.
Try sailing round the world on your own, and you'll suffer from sleep deprivation.
"I was so tired," said Ellen MacArthur, who broke the world record for the fastest solo circumnavigation of the globe in 2005. "Oh, God, it was just too much."
Doctors also suffer from sleep deprivation. "I was so tired I prescribed 20 times the right dose," one doctor said.
In our own very small way, even journalists suffer. Covering the tsunami, the combination of what we witnessed and a heavy workload kept us awake for days. This reporter looked and sounded drunk while doing a live shot from Banda Aceh.
"Researchers have compared the effects of alcohol intoxication to the effects of sleep deprivation," said professor Derk-Jan Dijk of the University of Surrey's Sleep Research Center.
But when you get right down to it, we don't know exactly how or why sleep revives us. What we can spend nearly one third of our lives doing, we know very little about.
"Sleep has been ignored by part of the scientific community and part of the medical community," said Dijk. "It's so much easier to study wakefulness."
At the University of Surrey's Sleep Research Center, they're trying to make up for lost time by analyzing the brain waves of sleeping volunteers like me.
They wired me up one morning at the center. I thought I'd had a good night's sleep and I drank four cups of coffee with breakfast, but within minutes, I fell asleep. Like many people, I'm sleep deprived without even knowing it. And sleep deprivation has a profound effect on how you function.
"You will find it very difficult to concentrate," said Dijk. "You will find it difficult to pay attention. You might find it difficult to speak and to construct sentences that make sense. Logical reasoning will certainly be affected."
Researchers at the university test brain function with psychometric tasks, such as identifying colors. They've discovered that a gene called "period 3" might be crucial. People with a short version of the gene did well picking yellow or green in the early hours. But 10 percent of humans have a long version: They struggled with the test and even struggled to stay awake.
After just 24 hours without sleep, everyone suffered mental impairment equivalent to being too drunk to drive a car, and researchers thought it unethical to push their human guinea pigs any further.
"It's clear that in animals sleep deprivation will ultimately lead to death," said Dijk. "If you keep rats awake for several weeks they will die."
Die of what?
"That is something that is not entirely clear," said Dijk.
Tony Wright has pushed it as far as any human we know of; he thinks his secret might be the raw food diet he's followed for 16 years.
"It was 1995," Wright recalled. "I decided I'd stay awake and see what happens."
At his first attempt Tony managed a weekend, 80 hours.