Britney Spears is adored by millions, but she's gone through periods of feeling very alone.
In a new E! documentary, "I Am Britney Jean," the pop star, 32, revealed that she's an introvert whom she believes is "not really made for this industry."
"I have always been kind of shy, since I was a little girl. It's who I am to be modest, so I really can't help it," she said, according to the Huffington Post. To perform, "I turn into this different person… seriously, bipolar disorder."
Spears also alluded to her 2007 public breakdown, after which she spent time in rehab. For the next few years, the mother of two tried to keep a low profile.
"There was a time in my life when I couldn't ever leave the house without 20 cars following me. I felt very alienated from the public," she said, later calling it a "dark period." "But as time passed, they lightened up and they kind of went away after I wouldn't come out of the house for like two years."