Archie Lasker may only be 11, but the Nowra schoolboy has seen the devastation a mental illness can have not just on the person diagnosed, but also the family.

And it is something he believes should not be treated with shame or secrecy, but talked about openly in the community so mental illness can become as acceptable as a disease like cancer.

Archie, along with more than 7000 other family, friends and people living with mental illness around the world, this week joined a global social media campaign called The Purple Project, opening the door on mental illness to try and lift the veil of secrecy and embarrassment.

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Two years ago, Archie's sister, Molly, was diagnosed with an eating disorder, and has been hospitalised numerous times over the past two years.

Like any mental illness, people with an eating disorder and their families often find themselves dealing with the issues that arise on their own and behind closed doors.

As swimming star Ian Thorpe this week discovered, although he has made no secret of his battle with depression, the response to his once more seeking treatment was far from accepting.

Thorpe revealed in his autobiography his battle with depression, saying: "I did it behind closed doors, where many depressed people choose to fight their demons before they realise they can't do it without help."

It's this shame and secrecy that Erin Casey wants to eradicate and if the response to her Facebook campaign The Purple Project is anything to go by, she is already starting to break down that proverbial door.

On January 29, 2014, Casey and friend and fellow advocate Lizzie Elsberg started a campaign on Facebook called The Purple Project. It is affiliated with Casey's own website for mental health awareness and education called Where I Stand which she began in 2012 after leaving treatment for an eating disorder.

Just 48 hours after the Facebook campaign started, more than 1000 people worldwide had posted their own purple prose on the site explaining why they're publicising their own brushes with mental health, and another 7000 had supported the project, including my own 11-year-old son.

And the numbers kept growing.

"Once people realise it is OK to talk about their own issues they want to do it abundantly and that is what we are seeing on The Purple Project," Casey says.

"This [The Purple Project] is bigger than we anticipated," she said.