I don't know if this is a universal feature of creative people, but I get very cranky when I'm not working in new stuff of some kind (music above all, but also writing, DIY gadgets, computer scripts, lately some video...)
The way I've come to see it is that my intellect, mind, ego, give it the name most suitable to your preferences, I mean that "inner voice" with a tendency to ramble that some of us have, needs something to chew on. I've read in several places the analogy that compares intellect to a dog, always in need of some "bone" to get busy on.
If you give the dog a few snippets of melody and words, it will chew and chew and at the end it may happen that you end up with a song. In the worst case scenario, at least you got the dog entertained, and leaving you alone, for a few hours. The same with a plot for a short story. The same with an idea for a videogame. For a mural on a wall for those who paint... Etc.
If you don't offer the dog some of those tasty morsels, however... Then guess what, it will chew on whatever it can find inside your head. And that's where paranoia, hypocondria, storymakings of all kind start to flourish, depending on each head's bearer particular characteristics. Not much to show at the end of such chewing, only a human being ruining one more day of his/her life in solitude and obsession.
I guess this is what the saying "an idle mind is the devil's workshop" points to. I also remember an entry in Charles Baudelaire's journals that said something like "The only piece too big to tackle is the one you don't start. That one torments you endlessly".
I have a feeling that there is some of this "devil at work" in those news you hear about some A list musician involved in legal quarrels for silly things, absurd feuds with band members, coming to and fro of accusations and versions of some worn out story... Huge reserves of talent and creativity, perverted in an extensive "soap opera", that would have found a better use in launching 3 or 4 whopping albums in one year... (even things like reunion tours are only remedial in my view, for sure those must be an incredible adrenaline kick, but there's no new stuff, no growth, no release for the creative energy.)
Like I said at the beginning, I don't think this tendency is universal; I'm sure some very damn good and successful musicians out there don't feel this kind of periodic "itch", and just see creativity as something they can "milk" on demand, when the time and the right offer arrive. But for sure there are a lot of unnoticed "dogs" on the loose out there, and if you're in that kennel it's a good way to give yourself a kick in the pants: whenever you think you're obsessing too much about something you shouldn't, perhaps that is the sign that you're not creating enough. The moral: don't starve your dog, he might stop being your best friend :)
I have a guitar and I'm gonna use it