Actor Dominic West has said playing Gloucestershire serial killer Fred West for TV has given him nightmares.
The drama is set to be broadcast on ITV and tells the story of the murderer through the eyes of a social worker who was sent to interview West in prison.
"I have this recurring dream where I'm perched on a wall and Fred West is trying to grab me and pull me down," said Dominic West.
The drama has been criticised for causing pain to the victims' families.
In March, West's daughter, Anne Marie Davis said the broadcast would cause "unimaginable distress to the families of the young girls who were murdered".
But the drama, called Appropriate Adult, has been defended by the actor.
"I think it's effective without being sensational in any way," he said.
"Thousands of people still go missing in this country every year and are never found.
"Fred West preyed on runaways without being caught for 25 years. We should not forget this case, because there could be others like him."