R+b star Rihanna is sick of her showbiz lifestyle because she hates having to pretend to be a "bubbly person" all the time.

The Umbrella hitmaker admits she is always forced to put on a happy face when she's on the road - even when she is feeling tired and miserable.

And the 20-year-old insists it often makes her feel worse.

She says, "I love what I do but, yes, this stuff does start to take its toll on you. Sometimes you get really miserable and on the edge, but people don't know why you're acting like that."

"You always want to be kind to people, so you're forced to be a bubbly person, but, to be honest, sometimes I'd just like to sit in a corner by myself and be quiet."