She said: “At 19 years old, diplomacy is not something that you understand.”

Recalling how directors and producers would tell her to keep quiet and do her job, she added to America’s ELLE magazine: “Basically, treating me like I’m a dog and I need to just follow their commands. Telling a 19 year old who’s intelligent, who was raised to not be that way at all, you don’t go, ‘Oh, how can I massage this?’ 

“Instead, I was like, ‘Where’s my sledgehammer?’ But the more I used the sledgehammer to break that down, the worse it got for me.”

And Shannen – who is battling stage 4 breast cancer – only turned to partying as a way of escape because she was “struggling” with her beloved dad Tom’s ill health as he suffered several heart attacks and strokes before dying in 2010.

She said: “People didn’t think I was private, because I was going out and was a party girl. But meanwhile, I was struggling a lot.

“[My dad] was my rock, my best friend, my mentor. As much as he struggled in his own way, I idolised him…

“It becomes a snowball effect. I’m running from my problems and my fears of losing my dad and the pressure of it. I went through an incredibly self-destructive stage.”

Last year, Shannen reunited with her former castmates on ‘BH90210’, a spoof show in which they played exaggerated versions of themselves, but despite her friend and co-star Brian Austin Green’s encouragement, she was initially reluctant to sign up to the project.

She said: “I had already done two 90210s by that point. I didn’t really see it as something that was going to help, but I did feel that it could stir up stuff from when I was 19 years old.”

But now, the actress is grateful she made the series, even though it hasn’t been renewed for a second season.

She said: “I’m very grateful I did it. It was nice seeing everyone again from a new perspective.”