The 23-year-old singer based the album 21 on her break up with her ex-boyfriend and admitted that booze helped get the creative juices flowing.
She told The Sun, 'I used to have to lock myself away in my house, get pretty drunk and write a drunk diary and that was the first time I could admit things to myself.
'A drunk tongue is an honest one in my opinion and the next morning I would read it through with an awful hangover and, in the cold light of day, had to absorb my feelings about myself. I was a bit scared that I wouldn't be articulate enough.
'When I was 18 or 19 I didn't regret anything, I was very much a teenager and thought I knew it all and that there was nothing else I could learn.
'I started realising my own flaws and my disappointments and I started regretting a lot of stuff. It was quite an awakening.'
Talking about her career, she said that one of the low points was having her track rejected for the Jake Gyllenhaal and Anne Hathaway movie Love And Other Drugs.
She said, 'I really wanted to have the soundtrack for Love And Other Drugs.
'I was in for a good shot but I submitted the wrong song. I love that kind of movie. Maybe next time.
'I want to do a Martin Scorsese film. I don't know if I am trained enough to offer something that good for one of his movies.'