Why are many gifted kids more hyperactive then most kids?

In movies and on TV. Smart children are depicted as overly serious and basically have no childhood outside of academies. While this may be true for some no child is the same.

A lot of them had a lot more energy then even some od the other kids. Had a very well developed sense of humor and honestly many were still kids at heart.

I have noticed there are some kids. That maybe has a higher then average intelligence or even a average one. But thier parents basically gave them no life outside of academic work and some of them were more serious then the other children.

Why are many gifted kids more hyperactive then most kids?
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