I second the Webb et al suggestion, and I've also found the Eides' work helpful (The Mislabeled Child).
For my daughter in K, we addressed this via occupational therapy, which included some sensory integration therapy. There was some progress--and with time she was growing out of some of her hyper-sensitivities--but we eventually decided that we were working too hard at making a sensitive/overexcitable kid try to fit in to a noisy and crowded classroom. After spending time in her class I realized that I felt overstimulated too! The teacher was outgoing and even boisterous, and the energy level was high. Since that K year we've tried to check out teacher possibilities in advance and ask for a more soft-spoken teacher, when there's one available. We've had friends deal with this by seeking a part-time school placement, or by asking if their child could spend extra time in a quieter space in the school, like the library--this works better for older kids, obviously, since schools don't like little ones to be traipsing to the library unaccompanied.
