Ian Thorpe contemplated suicide during his days as the world's leading middle distance freestyle, the 30-year-old told the BBC on a tour of promoting his autobiography This Is Me.

Treated for depression since he was a teenager, Thorpe took to drinking during the night to cope with his condition on the way to the 2004 Olympic Games. In Athens, he retained the 400m crown and claimed the 200m freestyle title, his form indicating that he spent most of his time healthy, engaged and doing the things that need to be done to win in the fiercest of competitive cauldrons.

"I realised that I had depression early," said Thorpe. "I was having treatment for depression when I was a teenager. Depression comes in bouts. You can feel okay most days and then just get hit with it. I experienced that through what was mostly a very successful swimming career.

"I have struggled with it before but I feel like I am on the other side of it. There are still times that are really tough for me, but I feel as though I know enough about it."

Asked whether he had ever contemplated suicide, he added: "Yeah, I wouldn’t talk about it otherwise. It’s not something that is a throw-away line. When you go through what the process of what it would be like and it becomes and obsession in your mind where all rational thought is devoid in that situation you realise that this has gone beyond just a thought. When you are trying to get it out of your mind rationally and you can’t. To consider it as being a rational solution to the way you are feeling you realise this is a problem, that this isn’t just a fleeting thought or feeling.

"This is a very clear guideline that you do need more help and that you’re not in control of your life and that the irrational thought has taken over."

Thorpe returned to swimming in the pst 18 months but missed the cut for the London 2012 Games. He is now working in two-year cycles, his next mission the Commonwealth Games in Glasgow, via having a crack at selection for Australia for the World Championships in Barcelona next summer.