Hallucinations in non-morbid conditions Hallucinations in the general population are associated with victimization experiences, average and below average IQ and female sex. A multitude of circumstances can trigger hallucinations in normal persons (as well as clinical populations). These include deprivation (food, sensory, sleep), fatigue, during going into or waking up from sleep, sleep-related states, life-threatening states, bereavement, grief reaction, prolonged perceptual isolation, sexual abuse, religious ritual activities and trance states. Subjects may report hallucinations in conditions of increased external stimulation (e.g., when in a crowd), decreased external stimulation (e.g., when alone at night) or when there is a particular, usually repetitive, background noise (e.g., being close to fans, washing machines). It is common for people (especially older people) to see, hear or feel the presence of the deceased person during bereavement.