I remember being tired all day long after waking up many time during the night to check the progress of my renders or to tweak it and restart. And then I got a math coprocessor so I could wake up more often in the night to check my renders.
I too slept badly because of povray rendering. But I just had trouble sleeping with the fan noise.
I would just set them before bed and then check them before going to school in the morning, and set another one running, of course :D
You lucky. I always dreamt of one, that and a TARGA graphics card. The last one not only for the looks but speed as well. Converting a *.TGA to a indexed color took a considerable amount of time.