I think that there are two kinds of hyperactivity, one introverted and one extroverted. The extroverted kind is what happens when the home team is winning and everyone is cheering. Take away the social context, and the level of excitement drops. The introverted kind is more what I have--the kind where someone does something like have an "aha moment" in science, or discover a new way of thinking about something, and is so stimulated about it that he can't sit still and starts to pace or run around the room. Do the other aspies here relate to having this "introverted hyperactivity"?
I am noticing more and more how most people, sometime around late adolescence, become less excitable and "hyper" in almost all ways. What I mean is, when many kids get to the beach, or see a puppy, or any number of things that make them happy, they will start walking faster or running, talk excitedly, etc. For some reason, this is rare in adults even when something surprising and good happens to them.
I lost much of the tendency to be physically hyper too in early adulthood, but I'm coming to believe that this is mostly because I developed a chronic illness around 15. My mind, to the contrary, has stayed as hyper/excitable as when I was younger. So when I'm tired I'm less likely to move around in a hyper manner, but I will still talk faster and louder when excited. When I'm too tired/lazy to do even that, I will just think faster. So being ill has made me "think too fast for my body", and made me more irritable--when I have moments of feeling well I tend to run around in bursts more like a kid and let off steam.
I think the fact that others' excitement has gotten "toned down" in early adulthood is a big part of the reason I still feel like a kid (along with my active imagination). Unfortunately, even most aspie adults I meet don't have this trait, at least not to the extent that I do. I'd really like to find a place where other people have this "introverted hyperness" too, so that I don't feel like "too much" around them. Does anyone know of a place where this is the general tone??