Sara Bareilles had writing block so badly she worried she'd never write another track for her latest record.

The 'King Of Anything' singer became panicked when she couldn't finish any tracks for 'Kaleidoscope Heart', and it took a huge breakthrough in the shape of the track 'Uncharted' to get her back on track.

She told BANG Showbiz: "I was having a terrible bout of writers block and couldn't finish a song for the life of me.

"It went from being a nuisance, to actually being really scary. I was having irrational thoughts of, 'maybe I'm never going to write another song again, maybe it's all been a fluke; maybe I actually can't write songs?'

"You start reaching all these incredible new depths of self doubt and then 'Uncharted' just came out of nowhere. It was a place for me to put all those fears, and it was like a lightning bolt.

"As soon as that was finished, the rest of the record came together."

Sara, 31, added when she hits her stride, a song can come to her very quickly, and a quick flash of inspiration resulted in her biggest hit to date, 'Love Song'.

She added: "I've been writing for years and I have songs which came out in a couple of hours.

"'Lovesong' was a very quick write, it came in a couple of hours, sometimes when it comes out quickly like that, it signifies you may be channelling something. Those are really special songs."

'Kaleidoscope Heart' is out now and Sara is currently on tour in Europe with Maroon 5.