Schapelle Corby, who was sentenced to 20 years' jail after being caught in October 2004 at Bali's airport with 4.1kg of marijuana in her boogie-board bag, is still waiting for the outcome of her clemency appeal lodged a year ago.

Mercedes, a regular visitor to her sister in Bali's Kerobokan prison, says Schapelle is not coping.

"Some days she doesn't speak and just has tears coming from her eyes although her face is not crying, just her eyes," Mercedes has says in today’s New Idea magazine.

“A few weeks ago, she came out to a visit with her hair all short, frizzled and burnt.

"She refused to tell me what happened but it looks like she had set it alight."

It is not the first time Corby’s mental health has been in the spotlight.

A clemency application, lodged in March last year, centered on Corby’s mental welfare and feared she could endanger her life.

The 33-year-old Queenslander has been diagnosed by three psychiatrists as having major mental problems, and has been on anti-psychotic and anti-depressant medication for three years.

A Supreme Court judge considered the bid and delivered his opinion to Indonesian president Susilo Bambang Yudhoyono's office in July.

"When we put in the clemency (bid), the law was that we would have an answer within seven months, but it changed," Mercedes said.

"Now there is no time limit and we have no idea when the answer will be. So we are just waiting and waiting."

with AAP