Just how great an actress is Oscar winner Tilda Swinton? She's such an amazing actress that she turns sleeping into a work of art.

Literally.

Yes, this sounds too crazy to be true, but New York Daily News reports that Swinton's latest project isn't a movie at all but rather a nap, as the acclaimed actress spent most of Saturday sleeping inside a glass box at New York's world famous Museum of Modern Art.

And this isn't the first time Swinton has grabbed some shuteye in front of crowds of puzzled museum-goers; she's been doing it on and off since 1995, when she debuted the work of performance art, which she calls "The Maybe," at the Museo Barraco in Rome.

If watching Swinton sleep sounds like your idea of a good time, there's good news and bad news: She will be doing it again, but nobody knows exactly when.

"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," MoMa said in a statement. "Those who find it chance upon it for themselves, live and in real-shared-time: now we see it, now we don't."

Talk about taking celebrity watching to a whole new level.