I got a set of these for my bed, and although my hair is baseline pretty wild no matter what state of existence I'm in, the overnight tangles have pretty much stopped. If I put my hair up in a scrunchie, I'll usually wake up with it more or less still intact, too (which is especially nice if I'm late for my ~morning power walk~ around the neighborhood). Most of all, though, it's soooo nice to sink your face into these in the hot summer, especially when your AC is subpar (*glares at mine from across the room*).
Promising review: "Couldn't afford silk so ordered these. I love them. I've heard that sleeping on cotton is like rubbing your face on steel wool all night since that's how delicate the skin there is. All I know is I shower and style my hair at night and after sleeping on these, my hair looked freshly blown dry the next morning. I'm not exaggerating, hair looked the exact same in morning as it did after I styled it the night before. So, if this material is that nurturing to my hair I can only imagine how my face is loving it. I'm hooked and will be buying more colors." —BinaryCode
Get a set of two from Amazon for $9.99 (available in seven colors and three sizes).