Britney Spears' alleged longterm battle with mental illness is set to be exposed in a new book.

The singer has been showing every sign of getting her life back on track in recent months, but, in Stalking Britney: Britney Under Seige, author Ian Halperin suggests that she may never put her troubles behind her for good.

"She's on a high right now, but her life goes in circles," Halperin tells In Touch.

“It’s like a roller coaster ride. She’s a person who is highly sensitive, and just one little thing could set her off.

“There’s no doubt, based on the last two years, that she is a highly unstable person.”

Halperin claims that the pressures of finding fame at a young age created deep insecurities within the singer that led her to attempt suicide four times following her split from ex-husband Kevin Federline in 2006.

“At 15, she had a huge breakdown and had to return home to Louisiana,” he reveals.

“She was very insecure and felt like she wasn’t pretty."

But, despite her continued troubles, Halperin calls Britney a “good mother, and a good person," adding, “In fact, she’s nicer than most of the stars I’ve met. But as Britney once told me herself, her life has always been two steps forward, followed by one step back.”