Demi Lovato: Picture: Instagram

Demi Lovato celebrated six years of sobriety in March, and she has now opened up about her struggles with addiction in her single 'Sober', which she unveiled to the world on Thursday.

Tweeting a lyric video which features candid snaps of her as a child and adult, she simply wrote: "My truth..."

On the touching track, Demi sings: "Mama, I'm so sorry I'm not sober anymore, and Daddy please forgive me for the drinks spilled on the floor.

"To the ones who never left me, we've been down this road before. I'm so sorry, I'm not sober anymore."

She later apologises to her fans, and admits while she would like to be a good example for them she is "only human".

Listen to the song here.

Demi has been open publicly with her battles with addiction - and her stint in rehab in 2010 - and emotionally celebrated her six year milestone during a concert in March.

The following month, she was snapped drinking from a red cup at Hayley Kiyoko's album release party - but she was quick to shut down her critics who doubted her sobriety.

She replied on social media: "I don't have to defend anything but it was red bull."

Demi is currently on tour in the UK, and while fans have been delighted with her performances she was disappointed to have to cancel shows in Birmingham and London due to swollen vocal chords.

She tweeted last week: "I've never had to miss shows due to my vocal chords or being sick in my LIFE

"This seriously sucks.. Haven't left my hotel room in 2 days now. Sick, bored and bummed out. (sic)"