How long can a human go without sleep? That depends on the gender, age, and occupation. Anyway, sooner or later the brain will need a rest. Either people want it or not, they have to sleep, as the lack of rest causes an over release of cortisol and adrenaline, which results not only in extenuation, but some hallucinatory visions too.
Boraie Development said the truck drivers even have a term for that, “seeing the black dog”, which signals the time for them to pull on the right and have a rest. Among people who tested their max were Randy Gardner, who did not sleep for 11 days for the purpose of a research for his school project, and a British woman who won a competition in 1977 who spent her nights in a rocking chair, battling the sleep for 18 days in total. Other people who succeed going long without sleep are those with FFI (Fatal Familial Insomnia).
It is not because they want so, though. A defective gene causes them to lose sleep, while the nervous system misfolds “prions”. The misfold proteins affect the thalamus, the area responsible for sleep, worsening their situation in the long run and bringing the patients to dementia and sudden death.