Britney Spears reportedly takes so many breaks while filming US The X Factor due to Attention Deficit Hyperactivity Disorder.

The pop songstress recently joined the coveted judging panel of the TV talent show alongside Demi Lovato and returning stars Simon Cowell and L.A. Reid.

Britney sparked controversy for walking off set on her first day on the job last week, leaving an empty judging seat for over four contestant performances.

Radar Online reports that Britney leaves spontaneously due to her medical condition, as it makes focusing difficult.

'Britney was diagnosed with Attention Deficit Hyperactivity Disorder in her teens and used to take medication for it,' a source told the website. 'Britney''s current team of doctors strictly prohibit her from taking Adderall or Ritalin, which are commonly given to people with ADHD.'

Producer and co-star Simon supports Britney and has afforded her allowances to take breaks whenever she wants.

'Simon was made fully aware of Britney''s medical history before the contract was signed. It''s not alarming to Simon at all and he is fully supportive of Britney doing whatever she needs to do during filming,' the source revealed. 'Simon would have been surprised if she hadn''t taken breaks during judging last week, this means she is involved and engaged in the process.'