Every office, whether in the home or in a boring office park with glaring flourencent light, should have a second chair that isn’t behind a desk. A sofa is best (because naps are important) but any chair would do. Even a bean bag chair on the floor.
If I’m stuck on a tough problem it doesn’t get solved staring at my computer screen. It gets solved sitting away from my desk and staring out the window or at the wall.