is waking up. Hallucinations can also be associated with drug or alcohol use (particularly deliriants ), sleep deprivation , psychosis , neurological disorders , and delirium tremens . Contents [ hide ] 1 Prevalence 2 Types of hallucinations 2.1 Auditory hallucinations 2.2 Olfactory hallucinations 2.3 Hypnagogic hallucination 2.4 Peduncular hallucinosis 2.5 Delirium