Things got a little too much for Cowell, 50, as he started work on the latest series of "The X Factor" in America and he was struck down with nervous exhaustion.
Quoting updates from Tom Bower's book on Simon, reports say that "the collapse was the real reason why he missed filming on the audition stages of the show, when he was said to be suffering from bronchitis", reported Sun online.
He apparently told Louis Walsh, "I desperately need peace. I'm craving normality. I've got to work out my demons and come out of it."
Cowell even said he felt like he was turning into a "weird vampire" because his lifestyle meant he would only reply to texts and emails from friends during the night.
His doctor ordered him to cut out all medication and health supplements to help his body recover, and was also told to stop smoking.