That's it exactly! I have had this for nearly 14 years, and have been to countless doctors, mopts of whom say I must have an anciety disorder, even though I'm telling I'm NOT feeling anxious about anything! Like you say, I can be in the most relaxed state, but still have this underlying nervousness/jittery feel - I even felt like this on a beach holiday in Thailand, where I certainly wasn't worrying about anything! I have been to see psychologists and counsellors and various other therapists in case I do have some kind of emotional issue, the last of which I saw in March this year, who pretty much told me there's nothing wrong with me 'in my head' :-) Which I have always known, but docs, who don't know what's wrong with you, are quick to jump at the depression/anxiety angle. Subsequently I have been on and off antidepressants for years, but even while on them I have still had all the usual symptoms.