`Circus` tour taking toll on Britney Spears

London, April 24: Pop star Britney Spears, who is on a world tour called `Circus`, is struggling with her energetic dance routines as the high-voltage performance makes her dizzy and nauseous. It also costs her clumps of her hair.

In one of her most recent shows in North America, a suspended dancer yanks off a handful of hair from Spears` head as he attempts to pull her into the air with him, reported contactmusic.com "The choreography is insane. It`s so fast it is really taking its toll on her (Britney). There is one move during (the song) `Touch Of My Hand`, where two guys dangle from the ceiling and pick her up upside down, which is really getting to her," said a source. "She spins around for nearly five minutes some nights. The blood rushes to her head and when she gets down she complains of nausea and dizziness. There have been a couple of times when she ran off stage and vomited," added the source. IANS