No, Tilda Swinton isn’t practicing for a role in “Sleeping Beauty,” she’s just publicly sleeping in a glass box for the sake of art.

Visitors at the Museum of Modern Art in New York got to observe the Academy Award-winning actress taking a snooze in a glass box on Saturday. (Check out Gothamist's photographs of her unusual MoMA performance.)

The actress wore shoes, a light blue shirt and dark blue pants, while lying on white bedding with eyeglasses beside her, Reuters reported.

According to one of Gothamist's photos, a description card of the performance-art piece labeled “The Maybe” read: “Living artist, glass, steel, mattress, pillow, linen, water, and spectacles.”

A source told the New York-oriented website that all the performances by the 52-year-old actress have been and will be unannounced and that the box she naps in contains only a water jug and cushions.

It’s set to be staged six more times throughout the year, and the box with a passed-out Swinton will be located in different parts of the museum.

The performance lasts for the duration of the museum's operating day, the insider said.

In any case, it’s not the first time Swinton has presented this piece.

“The Maybe” was featured first at the Serpentine Gallery in London in 1995 and later at the Museo Barracco in Rome, People reported.

According to MoMA: "An integral part of The Maybe's incarnation at MoMA in 2013 is that there is no published schedule for its appearance, no artist's statement released, no museum statement beyond this brief context, no public profile or image issued. Those who find it chance upon it for themselves, live and in real-shared-time: now we see it, now we don't."