Here's why Dev Patel spent an hour staring in mirror

London: Actor Dev Patel says he used to spend hours staring himself in the mirror for his role in "Lion".

In an interview to Empire magazine, the 26-year-old star says his part in the film required a different kind of energy for which he went through a lot of things.

"It required an energy shift. I'm a super-hyperactive kind of dude and the role required a level of stillness. Saroo had this emotional pain, this weight. I spent eight months prepping and it was all a process of introspection.

"I travelled around India on trains to get a feel of what it would be like, I wrote diaries, I visited orphanages. Garth (Davis) would get me to stare in the mirror for an hour. It's amazing what you can see when you stop for a moment and really try to look inside yourself," he said.

He landed the role after a gruelling six-hour audition in which he worked through the entire script with director Davis and "lost his mind" at the end.

"At the end of it, Garth said, 'Before you go, I'm wondering if you could just scream?' I was like, 'What do you mean?' He said, 'I want you to roar like a lion. Let go of emotion and completely purge the pain you'd feel in Saroo's situation. You don't have to do it.'

"And I was like, 'Of course I have to'. So I did and I completely lost my mind. I was jumping in at the deep end," he said.