Demi Lovato was overwhelmed after watching her 'Dancing with the Devil' documentary series for the first time.

Demi Lovato

Demi Lovato

The 28-year-old star candidly opened up about her struggles with addiction and mental health in the YouTube series and revealed she had an "anxiety attack" after watching the documentary.

Demi told 'The Tonight Show with Jimmy Fallon': "I had a physical reaction the first time I watched it. Like - anxiety attack."

The former Disney star confessed that she found it "challenging" to be so open about private matters during the series and explained how she had to "work" on herself to make the revelations about her personal struggles.

Demi shared: "I had to work through a lot of things before I actually told my story on camera.

"But I've been working on myself and putting a lot of work behind the scenes to tell my story."

Despite her discomfort, Lovato suggests that working on the project has healed scars and described the series as "therapeutic".

Demi was recently praised by music legend Sir Elton John for being "brave" with her response to her addiction issues.

Speaking in 'Dancing with the Devil', the 74-year-old singer said: "When you’re young and you’re famous, my god, it’s tough. You are put up on a pedestal and you’re not supposed to be human.

"Demi Lovato is god, she’s fantastic, she’s perfect – but of course we’re not perfect, we’re all human beings. She’s human and she’s adorable and she’s brave."

Elton lauded Demi for opening up about her problems as he admits that he struggled "ask for help" during his own battles with addiction.

He said: "Isolation is the worst thing you can do. Ask for help. Asking for help was so hard for me because I thought I could do everything myself.

"The great thing about Demi is that she has opened up about her addictions and her problems and the stress and the pressure of fame at such a young, early age, and a lot of people are afraid to open up about it, and I think once you open up about it, you get the monkey off your back and you come out in the open."