The actor, who's currently promoting her post-Second World War drama The Aftermath, took time off from her career at the age of 22 after suffering from a mental health breakdown and being diagnosed with post traumatic stress disorder (PTSD).
Now aged 33, Knightley believes it's important for high-profile celebrities to speak openly about any mental health struggles they may have faced throughout their lives so as to inspire others to do the same.
"In what I do – and this is painting a dramatic picture – you’re damned if you do and you’re damned if you don’t," the Oscar-nominated actor tells Stylist, referring to using her role in the public eye to discuss mental health issues.
"You can say nothing and you’ll be despised. Or you can say something and many people will go, “Oh f*** you, you’re oversharing. Piss off."
Knightley continued, saying that if a young person "feels like they are breaking" psychologically and hears about a celebrity who once felt the same way, this knowledge could provide them with solace.
"But I had the money to get through it and that’s not the position a lot of people find themselves in. We have a government that hasn’t ring-fenced mental health care," the actor adds.
One of the predominant themes of The Aftermath, which sees Knightley star alongside Big Little Lies star Alexander Skarsgård and Terminator Genisys actor Jason Clarke, is the propensity for men to often conceal their true emotions, especially during the post-war era of the 1940s.
"That generation was particularly known as the silent generation, so we have moved on a lot from then... but do people still [repress feelings?]? Of course they do," Knightley says.
"And is there still that idea of masculinity that says you're meant to 'man up'? That, as we know, has led to a mental health crisis."
While initiatives like Movember place emphasis on encouraging men to speak more openly about their mental health, Knightley also highlights the importance of breaking down taboos around conditions such as PTSD, which is estimated to affect twice as many women than men, according to the US Office on Women's Health.
"A phenomenally high number of women have suffered from PTSD. We need to do more to tackle it – we have to look after the most vulnerable members of society," the actor states.
"Particularly when you’re looking at one in 10 children suffering from mental health problems. As a voting public, we’re not doing enough particularly for our young people, but actually for everybody."
In a recent interview with Glamour, Knightley recalled moments in her career when she "hasn't been able to cope".
“Ultimately, it’s nothing to feel ashamed about,” she said.
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