What are hallucinations?

A hallucination is an experience involving the apparent perception of something which is not present. It can be in any sensory modality (hearing, seeing, smelling, tasting, touching). The most common form is hearing voices when there is nobody around and nothing to explain them (for example a radio). A hallucination is experienced exactly as if it was a real perception, meaning that it can be confusing, distressing, and hard to understand for people. They can occur in lots of different conditions including severe episodes of depression, bipolar disorder, schizophrenia, and dementia. They can also occur in people when they don’t have a mental health problem. They commonly can occur when you are falling asleep or just waking up.