Michelle Williams loved the long dresses she wore for her new movie - because they were easy to urinate in.

The actress enjoyed wearing period costumes for 'Meek's Cutoff' - which focuses on settlers travelling through the Oregon desert in 1845 who then find themselves stranded in harsh conditions - because of the privacy the outfits offered when she needed a toilet break.

She said: "The dresses, they were ingenious for so many reasons. They actually do keep you quite cool, because they're cotton, and they also provide cover. Privacy is important to women, and when you're on the trail like that, so little is afforded. But with the dress, you can actually go to the bathroom in private. It provides an incredible shield. You could literally be in a conversation with somebody and just sort of drop down . I can't believe I'm talking about this."

Michelle was such a fan of the bonnets she had to wear, she and her co-star Zoe Kazan went out and bought some when shooting wrapped.

But the 30-year-old star admits one side-effect of the modest clothing was that it made her develop a repressed attitude.

She told Interview magazine: "It's like wearing blinders, really. But again, the lack of privacy on the trail almost created a sense of privacy when there is none. Zoe Kazan and I became close during the movie, and we missed our bonnets. I missed the whole thing. There were two Winnebagos that housed hair and make-up, wardrobe, ADs, changing, everything ... and we'd take our dresses off at night and I'd catch a glimpse of Zoe's ankle, and it became like pornography. When you're covered from head to toe all day long, you're not used to the sight of skin, and I would sort of avert my eyes because I'd feel like I was seeing something inappropriate."

"But we bought bonnets. We've been threatening each other to wear them in Brooklyn, but so far neither of us have been bold enough to break them out."