The 'Who's Laughing Now' singer warned fans to expect a darker theme on her next LP, as her current songs were written at a time when she needed to be uplifted.
Jessie J told the Daily Star: "There'll be a lot more pain in the lyrics on my next album. For the seven years before I signed my record deal I was in a bad place and I was scared that I couldn't get out of it. That's why I wrote such upbeat music, as a way of trying to escape how I felt.
"Now that I am happier, I won't be afraid to explore my pain. But in a good way; it'll be me saying that it's OK not to feel OK. Not every song needs a happy ending."
She added: "I'm writing ideas down in my phone every day for new songs and I want to explore every aspect of music more on the next album, from different styles to my voice to what I sing about to who I get to duet with."
Jessie J added that she had been inspired to try to debunk people's perceptions of her by Adele, who is apparently concerned about the reaction to her sorrowful 21 album.
"[Adele] said she's worried everyone thinks she's always going to be this broken-hearted woman because of the songs on 21," she revealed.
"Those songs were just a moment in Adele's life and that's what music should be, a moment in time, an exaggeration of that moment condensed into a three-minute song."
Jessie J revealed last month that she wants to record a "feminist" duet with Tulisa Contostavlos for her second album.
Who You Are is on course to be named as the biggest-selling debut record in the UK this year.
> Jessie J to remain "pop" for second album
Watch Jessie J in the video for 'Who You Are' below: