A man from Cornwall has begun an attempt to break the world record for sleep deprivation.
Tony Wright cannot use any stimulants during the attempt
Tony Wright, 42, from Penzance will have to stay awake beyond the current record of 264 hours, equal to 11 days.
Randy Gardner set the Guinness World Record in 1964 as part of a student science project in San Diego, US.
Mr Wright started his record attempt at 0600 BST at Penzance's Studio Bar. It is part of his research into the body's relationship to sleep.
He argues that parts of the human brain require a different amount of sleep and it is possible to stay awake and remain functional for long periods.
He cannot use any stimulants during the attempt and is hoping a raw food diet will help keep him awake.
He said: "I have done over 100 experiments with sleep deprivation lasting between two and eight days.
"I am pretty confident the first week of this attempt should be pretty easy but beyond that we will have to wait and see."