The former Downton Abbey star, who played Lady Sybil Crawley in the period drama, revealed she had been battling a disorder for the past 13 years while discussing the pressure she feels to look a certain way as a young actress during an interview with Britain's Daily Telegraph newspaper.

"I've had an eating disorder since I was 14," the 27-year-old said. "And I think that we can feed certain ideas of what beauty is and what success is and I just feel there has to come a time where those aren't the rules anymore, and then we can have a mature conversation about what that is about, and about depression."

Jessica added that she decided to open up about her battle because she hopes it will help others who may have the same problems and make them feel less alone. She also shared that being brave and talking about her struggle with other people and with experts has made her feel "less alone".

"(In) therapy, really looking at myself and deciding I was going to help myself feel safe and good and healthy, and talking about it," she said. "I felt so alone for so long, and I just hid. And then I started talking and held my head up and instead of saying sorry decided to tell myself that I matter."

The Victor Frankenstein actress admits she used to be guarded in interviews because she "shied away from things" but is now "learning to stand up and say: 'This is me, and that's OK.'"