Toni Collette got sick of making ''heavy'' movies.

The 45-year-old actress can next be seen playing an increasingly-unhinged artist and mother in horror movie 'Hereditary' and though she knew straight away she ''had'' to be a a part of the project, it wasn't what she was looking for at the time it was offered as she was keen to work on something light and funny.

She admitted: ''I was not looking to do a film like this. I had specifically said, 'I'm sick of heavy, I don't want to cry all the time at work anymore. I want to make some funny movies.'

''My agent called and said, 'I know what you said, but you need to read this.' And he was right. I loved it. I mean, I don't know if 'love' is the right word - it was more of a knowledge that I had to do it. It was so brilliantly written, so original.

''All actors really want is an opportunity to go for it, and I was given that opportunity in spades.''

The film marks writer-director Ari Aster's first stint behind the camera but Toni insists that was more beneficial to her work than a risk.

She told TIME magazine: ''I often work with first-time directors, and I actually think it's more beneficial than not.

''Ari was meticulously prepared - everything was so considered. But there still was a green quality to him, and I think that's actually a beautiful thing, because it means that they're open.

''I think people respond to things that are original and fresh and that they can see themselves in. The types of films that are being made I think are too safe, and this film isn't safe.''