The trial of a husband accused of murdering his wife as they slept in a camper van has heard he killed her because he dreamt she was an intruder.

The body of Christine Thomas, 57, was found in a camper van in a car park in Aberporth, Ceredigion, in July 2008.

Swansea Crown Court heard that her husband Brian Thomas, 59, suffered from a sleep disorder.

The prosecution says it is seeking a verdict of "not guilty by reason of insanity" against Mr Thomas, of Neath.

Prosecuting barrister Paul Thomas QC, in his opening words to the jury on Tuesday morning, described the case as "highly unusual".

He described how Mr Thomas killed his wife, his childhood sweetheart, because he had dreamt she was a man who had broken into their motor home.

The court was told Mr Thomas's disorder meant he was not in control of his actions when he strangled his partner of 40 years.

After commissioning evidence from sleep experts, the prosecution agreed his actions were involuntary and he could not be held responsible.

The prosecution has told the jury it will have a choice between the "not guilty by reason of insanity" verdict it would argue for, or the straightforward "not guilty" verdict the defence would seek.

The case continues.