The longest documented instance of a person going without sleep was 264 hours, reports Scientific American. Psychology Today explains that sleep deprivation alone has not caused any documented deaths, but cognitive difficulties resulting from sleep deprivation may lead to fatal accidents, such as car crashes.
Scientific American reports that people kept awake as long as 10 days in sleep experiments demonstrated impaired cognitive function, decreased motivation and limited perception. However, these subjects recovered after two days' worth of regular sleep.
The biggest risk to humans comes from limited mental functioning associated with sleep deprivation. It is theoretically possible for humans to survive up to 10 years of total sleep deprivation before dying from lack of sleep, claims Psychology Today.
In 2007, the Guinness Book of World Records stopped keeping track of sleep deprivation records because of perceived health risks, reports the BBC.