Perusing Flickr, we found this amazing ceiling in India made completely of inlaid stone (laid piece by piece by hand!). Probably a tad too involved to recreate in your home but if you consider using stencils this is a great DIY idea for a simple bedroom with an unexpected twist.
We keep our bedroom pretty spare, but a simple geometric pattern in one color would be a great detail to wake up to without it overwhelming the room. Careful if you have low ceilings though, this is one probably best reserved for a higher ceiling so it doesn't feel lower than it already is. Check out a video that breaks down the different ways to make stencils right here.
Image from The Mountain Label