Katy Perry says her new single is the "perfect last word" for her situation at the moment.

The ballad Wide Awake contains lyrics about moving on from a difficult period. Katy recently revealed how writing new material has helped her cope with personal heartache, following the breakdown of her brief marriage to Russell Brand.

The star thinks Wide Awake is a fitting end to her Teenage Dream era.

"I love this song so much. It was a song that I hadn't written for Teenage Dream," she told MTV News. "I was doing this movie and they asked me if I wanted to write an end-title song for the movie and I was like, 'I know exactly what I want to say.' I was really kind of dying to write another song at that point. I didn't want to wait until I did a whole new record, and it's kind of the perfect last word of me at this moment."

The track was written for Katy's new documentary Katy Perry: Part of Me.

Katy will premiere the dreamy video to accompany Wide Awake on Tuesday.

In the promo, Katy appears to be playing a princess. During her fairy tale journey she comes across Prince Charming, a poisonous strawberry, a cat and a young girl.