The 'Rolling In The Deep' singer revealed how she used to lock herself away at home and write a drunk diary in order to properly articulate her feelings.
"That was the first time I could admit things to myself," she told The Sun. "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."
The 21 star further claimed that the practice had helped her mature as a singer and a person by confronting her with her own "flaws and disappointments".
"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."
Adele previously confessed that the writing of 21, which was inspired by the loss of her first love, "broke [her] heart".
Watch Adele perform 'Set Fire To The Rain' below: