The television personality said she started feeling "a kind of numbness" and other symptoms while filming scenes for the civil rights film The Butler, and working to improve her "struggling network", the Oprah Winfrey Network.
The realisation dawned on the 59-year-old when she was being interviewed by Jason Russell, the director of the controversial campaigning video Kony 2012 who also suffered a very public nervous breakdown last year.
"I was sitting and listening to Jason Russell describe his symptoms, saying, 'Um, this sounds pretty familiar to me,'' said Oprah in an interview with Access Hollywood.
"In the beginning, it was just sort of speeding and a kind of numbness and going from one thing to the next thing to the next thing. I will tell you when I realized that I thought, 'All right, if I don't calm down I'm gonna be in serious trouble.'
"I was in the middle of doing voiceovers, you know? And I remember closing my eyes in between each page because looking at the page and the words at the same time was too much stimulation for my brain."
While Jason's condition deteriorated to the point that he was arrested for running naked in the streets of San Diego, Oprah set the record straight on her experience.
"I mean, I wasn't ready to go run naked in the streets. Let's make that very clear," said the actress. "But I had reached a point where I just couldn't take in anymore stimulation."