How many hours do you have to be awake before you start hallucinating from sleep deprivation?

3 days: It appears that going without sleep for at least 3 days may cause one to have hallucinations (visual, auditory, sensory). However, i don't believe it is universal. This is just the ballpark figure.

Sleep deprivation : General effects such a lack of focus, irritability, and memory issues can happen w/in a day. Hallucinations w/in a few days. This symptoms are primarily from lack of REM sleep, dreaming. When allowed to sleep and dream again you will dream a lot more even if you don't remember, until the body-mind is back in balance. Peace and good health.