And the use of hypnosis in science and medicine. Former President of the Section for Hypnosis and Psychosomatic Medicine at the Royal Society of Medicine, Dr Peter Naish, describes how this altered brain state is providing a useful new tool for researchers investigating how our brains function, as well as clinicians treating patients in the NHS.

Claudia visits the hypnosis unit at the Institute of Psychiatry, Psychology and Neuroscience at King's College, London, and finds out about a unique study that has volunteers, hypnotised, in a brain scanner while "thoughts" are inserted in their brains. The result: automatic writing. Just like Caravaggio, 400 years ago, painted St Matthew, inspired and directed by an angel as he wrote the Bible, volunteers in this study are told "an engineer" is inserting thoughts into their heads and controlling their hand movements as they write. Dr Quinton Deeley, Dr Eamonn Walsh and Dr Mitul Mehta tell Claudia how their research is shining light on our brains and the nature of thought and consciousness.

Producer: Fiona Hill.