(Cover) - EN Showbiz - Natalie Portman only slept for five hours a night while shooting her new movie as the schedule was so rigorous.

The actress stars in Black Swan, about an experienced ballet dancer who comes up against a young novice rival. Although the movie sounds like it could be a light-hearted dance production, the brunette beauty revealed the filming experience was far from it.

She has confessed the work completely took over her life, so much so she didnt even have time to get enough sleep.

Basically, I didnt do anything except work, she told the New York Times. There was no, like, meeting up with friends for dinner or going to the movies. Wed do 16-hour days, then Id go home and work out, because I had to stay in shape, and Id prepare for the next days scenes and then get maybe five hours of sleep. It was really, really extreme.

The 29-year-old admitted that there were few laughs during the intense rehearsals. She described the atmosphere on set as frightening, building up viewers expectations about the psychological plot.

It was a very serious set, Natalie said. Not a funny, silly set at all. It was scary, disciplined and rigorous, and I think, in a way, that fit into the mindset of the characters.

The star explained she has always wanted to combine her big screen work with ballet dancing. Natalie studied the art when she was a young girl and starring in Black Swan has marked the fulfilment of a dream for her.

Id studied ballet, the actress explained. From the age of 4 to about thirteen, at the American Dance Theater Workshop on Long Island, which is associated with the Eglevsky Ballet, and from the time I became an actress I think I always wanted to do a ballet film. (C) Cover Media