In the summer of 2008, police arrived at a caravan in the seaside town of Aberporth, west Wales, to arrest Brian Thomas for the murder of his wife. The night before, in a vivid nightmare, Thomas believed he was fighting off an intruder in the caravan – perhaps one of the kids who had been disturbing his sleep by revving motorbikes outside. Instead, he was gradually strangling his wife to death. When he awoke, he made a 999 call, telling the operator he was stunned and horrified by what had happened, and unaware of having committed murder. Crimes committed by sleeping individuals are mercifully rare. Yet they provide striking examples of the unnerving potential of the human unconscious. In turn, they illuminate how an emerging science of consciousness is poised to have a deep impact upon concepts of responsibility that are central to today’s legal system. After a short trial, the prosecution withdrew the case against Thomas. Expert witnesses agreed that he suffered from a sleep disorder known as pavor nocturnus, or night terrors, which affects around one per cent of adults and six per cent of children. His nightmares led him to do the unthinkable. We feel a natural sympathy towards Thomas, and jurors at his trial wept at his tragic situation. There is a clear sense in which this action was not the fault of an awake, thinking, sentient individual. But why do we feel this? What is it exactly that makes us think of Thomas not as a murderer but as an innocent man who has lost his wife in terrible circumstances?
