I think it takes a long time, like up to two week to start experiencing hallucinations, but the brain differs from person to person, so there is no real way to tell at what point a person might start experiencing hallucination. While sleep deprivation up to a week can cause things like lose of memory and lack of concentrations are common, it usually take longer to start actually hallucinating. The brains different for everyone though, if you think you are hallucinating I'd get your ass to a doctor.
For me it takes more than 96 hours constantly awake for hallucinations become apparent.
If I sleep less then 4 hours each day for 3 or 4 weeks then I just feel tired and have the shakes. (Good times :tongue
There was an experiment that some people took part in. One person made 8 days without sleeping. Also there is a condition called Fatal familial insomnia where the person effected does not sleep for more then 6 months and death is the result.
I have not had restorative sleep in one month. I know I have been in the early stages of sleep but it's kind of like drifting off into a dream and awaking right after. Not sure how long a person can go without restorative sleep.
I read somewhere that there's a rare genetic disease that kicks in sometime mid life and stops you sleeping, they last about half a year or so. I know when I was getting insomnia it nearly drove me nuts, I was hallucinating pretty bad at one point, "luckily" I had my accident but I was a mess afterwards.
Hmm well I remember a reality TV show where contestants had to stay awake for 7 days, the person who was able to stay awake the longest won £100,000. Anytime they fell asleep they would lose £1,000 every 10 seconds. It effects people in different ways. Typically, hallucinations start after 72 hours without sleep. Typically. But that doesn't mean to say it'll take 72 hours for you. Could be shorter, could be longer.