Oscar Pistorius sleeps with a security guard at his door since he shot dead his girlfriend Reeva Steenkamp, the High Court in Pretoria heard on Monday.

The emotional paralympian told the court he had trouble sleeping since Steenkamp's death on February 14 last year.

"A security guard stands outside my door at night," he said.

"I wake up in a state of complete terror at the slightest noises."

Pistorius said that after the shooting he never wanted to handle a firearm again.

He said one night he could not sleep and climbed into a cupboard. He asked his sister Aimee to stay with him.

The court heard that he was put on antidepressants and sleeping tablets after he shot Steenkamp in his Pretoria home on Valentine's Day last year.

Pistorius told the court about his parents' separation when he was six years old and that his mother passed away when he was 15.

He spoke of the close relationship he had with his brother Carl and sister Aimee.

Barry Roux, for Pistorius, asked Pistorius to explain the difficulties he faced after he was born without fibulae in both his legs.

"I have prosthetic legs which has helped me overcome those disabilities," he said.

Pistorius told the court about his amputation and when he got his first prosthetic legs.

He is on trial for the murder of Steenkamp, who was shot through the locked toilet door of his Pretoria home on February 14 last year.

He says he had mistaken her for an intruder. He has pleaded not guilty and in his plea statement denied he had argued with her shortly before the shooting.

He also faces two charges related to contravening the Firearms Control Act, to which he has denied guilt.