Portman, who won an Oscar for her role as a ballerina in the flick, has shared her regret at not taking enough time to recover from the gruelling schedule before starting new film Thor.
The 29-year-old told Total Film: 'I loved Darren Aronofsky, and working with him was a deeply fulfilling experience, but I just showed up for Thor spent. I probably should have gone into rehab.'
However, Natalie said getting the opportunity to work with Thor director Kenneth Branagh was worth enduring such a hard period.
She added: 'I must have watched [Kenneth's] Much Ado About Nothing about 500 times, I love that film so much.
'He was one of the first people I've met that I was excited about when I met them. When I worked with him, it exceeded my expectations.'