LOS ANGELES (REUTERS) - Swedish director David F. Sandberg found himself being courted by LA's elite when his two-and-a-half minute short film on the video sharing site went viral.

"I was getting all these e-mails from Hollywood about people wanting to talk to us and like I had to make a spreadsheet of everyone who I'd talked to in Hollywood and what they'd said the last time and it was managers and agents and producers and studios and it was, 'How can a two-and-a-half minute short do all of this?', but it was every film maker's dream, you know."

Sandberg's mini-horror movie, called Lights Out, has since been turned into a feature-length film.

The updated version has a new cast and the story focuses on a family plagued by a spectre.

But despite the big screen treatment, Sandberg was allowed to remain in the director's chair.

"I was kind of surprised that they let me direct it because I'd never even been on a film set before. I don't know if they thought I was more experienced than they thought I was because they'd ask 'oh, do you have a Director of Photography you like to usually work with?'. No, I'm the one shooting it and editing it and all of it."

Lights Out opens in US cinemas on Friday (July 22).