To Dream, Perchance To Sleep

Ever feel tired but not sleepy?  How about--immeasurably more vexing--sleepy but not tired?  This is what makes me an insomniac, because I'm pretty certain that I fall into that [vast and ill-defined] category.  Hmmm, categories...  I am led to believe (from sources such as Stephen King novels) that most insomnia is actually just the sufferer's inability to get to sleep and sleep well.  The Mayo Clinic says that insomnia is that and waking in the night and not feeling rested in the morning.  Um, bingo.  I think it's some sort of disconnect between my brain and my body (perhaps my autosomal and somatic nervous circuits) that leads to my autosomal systems gearing down (heart rate, breathing, smooth muscle...) while my brain is a barely contained maelstrom of discordant thoughts, tumbling over each other to escape my head into the tangible world.  I try to write stuff down, get it out, and hope it will be gone, but it is summarily replaced with a new stream of consciousness.  That miscommunication seems the most likely culprit.