The murderer of Lancashire teenager Sophie Lancaster is to serve four more months on top of his life sentence.
Brendan Harris, 20, has been found guilty of an attack on a nurse at the secure unit he is housed at near Preston.
He was transferred to Guild Lodge, Whittingham, after developing paranoid schizophrenia three years into his life sentence for killing Sophie and wounding her boyfriend.
Harris was 15 when he was convicted of the attack in Stubbylee Park, Bacup. It is thought the couple were singled out because they were dressed in Goth clothing.
Harris was sentenced to life with a minimum term of 17 years and began his sentence in a young offenders’ institution but following a decline in his mental health was transferred to Guild Lodge in 2008.
Preston Crown Court heard in January, following an incident at the psychiatric unit during which a fellow patient had to be restrained, Harris became agitated at being asked to keep away from his room which was opposite the seclusion room.
He later became involved in an argument with the staff. When they tried to restrain him and reason with him, he lashed out at a nurse and punched him in the face, breaking his nose.
Sentencing him, Judge Christopher Cornwall said: “It seems to me you had no intention of co-operating.
“This was effectively keeping the staff from doing their quarterly hour checks on the other patients to ensure their wellbeing. Guild Lodge behaved entirely properly in accordance with methods that had been decided with you.”
Judge Cornwall said the sentence would send a message to others in prison or hospitals for long periods that they have “little to lose” by committing such acts.
He added: “There is a real public interest in passing a consecutive sentence to the minimum term.”
During his trial, Harris admitted the attack but said he was acting in self-defence as he said he felt threatened.