There is a lot written on the topic of brain drought/creative block. I've read suggestions that you should plow through the nothingness-- that persistence will lead to a kernel of an idea, and it will take root. Others say, get away from your work. It does no good to hack away at something that isn't there. What do you do when you have a drought of ideas?
Fortunately, I have several different projects going on. Like I mentioned in a previous post... being busy spurs my brain to work a little harder. The ideas I return to are hardly ever novel. The fun (though hard) part is taking a familiar idea and making it my own. Sometimes it doesn't work and I want to crawl into a hole and shrivel up/give up. Sometimes it does work, but someone already came up with the same genius idea so you can't use it because it would be copying (kind of).
And once in awhile, you come up with something that seems to be unique and so you proceed tentatively at first. And eventually, all you want to do is work on your idea. Forget the bathroom, forget food or water, forget sunlight... Does the light table count?