Shahrukh Khan continues to practice the body language and the speech patterns of his autistic character even at home.

Before Shahrukh Khan played the autistic character in My Name is Khan, Karan Johar met Londoner Chris Aston who suffers from Asperger"s Syndrome and his wife Maxine who wrote a book on how to cope with a spouse suffering from the disease.

Says Karan, “Shibani and I met the couple. They were gracious enough to meet us in London. And that couple"s relationship became the basis of Rizwan and Mandira"s relationship in My Name is Khan. At its core level this film is a love story."

Continues Karan, “My writer Shibani Bhatija researched extensively on various aspects of an autistic disorder and contacted the various National Autistic Centers. Shibani and I personally met a lot of autistic people, took notes went to You Tube. Then Shahrukh did his own research."

Karan admits this has been the most difficult film of his career. “It has taken its toll on me and Shahrukh. It"s true Shahrukh remained in character as Rizwan Khan even at home. At home in his body language he"s always Rizwan. I see him doing it all the time. I don"t think he has got out of it. Even when he"s with his children at home."

Karan cuts down the theory that Shahrukh"s disorder is inspired from Tom Hanks in Forrest Gump.

“It"s not Tom Hanks in Forrest Gump at all. That was a totally different strain of autism. It"s nearer to Dustin Hoffman in Rain Man, though still very different. It"s what we call high-functional autism. You can have a regular life, be married, and have children. But the syndrome does convey a fair amount of quirks and eccentricities. But his character is not essentially neuro-typical. The film has made me understand human behaviour and how to be compassionate and humane."

The film has sapped Karan"s energies. He needs to take a break. “I need to go away for a month. I don"t think it will happen. But no harm in dreaming."