If your child cannot control their energy level, and discipline for situations has no effect on them, it's a sign. Like, if you have warned a child "no" every time they attempted to climb up and stand on a counter, and then firmly disciplined (not wimpy time outs, those perpetuate wild behavior) them the next time they did it, EVERY SINGLE TIME, and 35 times later, they are still springing up onto the counter jumping around completely unable to stop themselves....there may be a neurological thing going on. If your child is "always on" and never getting tired during different parts of the day-like an afternoon "down time" or almost nap thing, they have more energy than most. I know kids who are wriggly and squiggly and climby just because their parents don't discipline them to be still at times, and ones who are completely incapable of stopping their body from constant, wired energy. The second case is rare. Most kids can control their oodles of energy when they have to with enough work from parents. My kids are running around like banshees right now, after a full day of playing at parks, no naps, not nothing, WHY ARE THEY HYPER WHILE I CAN BARELY TYPE, but I know if I tell them to stop, they will. I'm just letting the burn out before bed. If it's impossible to control the behavior no matter how firm and clear you are, they may be hyperactive. Olympic Swimmer Michael Phelps said he literally could never calm down, so his mom threw him in the pool. Perfect for a super strenuous sport!