This is actually how my hair is most of the time, since it's easy and I'm lazy. All I do is, before bed, detangle with brush or wide tooth comb and then go to town with a boar bristle brush for a few minutes. After that, I palm through some hair oil (Better Botanicals Herbal Hair Oil is a personal fave), shake out the roots upside down, and go to sleep. I wake up with moisturized, tousled waves that will stay intact until I get them wet. Repeat the process each night for as many as you and your hair can stand until you have to wet/wash/CO wash.

Because my hair is short (above the shoulders when curled) I find it impossible to get good second day curls, as sleeping mooshes my hair into strange positions. When it's brushed out and greased up, however, it just mooshes into messy waves. I've gone up to 4 days just doing this over and over each night. And it's big and full and messy, which is how I generally prefer my hair. If you're looking for less mess, I'd just use a little more oil or a light styling cream the next day to wrangle it.