Miley Cyrus is grateful to have found fame as a singer outside of her Hannah Montana TV series - because she isn't as happy-go-lucky as her on-screen alter ego.

The teen sensation, daughter of country singer Billy Ray Cyrus, shot to international fame on the kids-friendly Disney show, playing the ever-optimistic schoolgirl-turned-pop star Hannah.

The 15-year-old's real name is Destiny, but she gained the nickname Smiley - which was later shortened to Miley - because was such a happy child.

But she insists she is relieved when she is not playing Montana - because she isn't fond of the character's incessant grinning.

She says, "I feel like I have to smile a lot as Hannah Montana and my mouth ends up getting tired. I don't like smiling much."