My son is four years old. As I watch him, I am noticing more and more of my own behaviors become evident in his own. He's sleeping 2 hours at night, up for several and then sleeping 2 more hours with no signs of being tired in the morning. He will laugh hysterically/get overly excited at random insignificant things. (Such as getting a Popsicle) And he talks almost non-stop from the moment he wakes up until he finally passes out. His conversations topics range from something he just saw on TV to things that happened weeks or even years ago. While I have been trying to chalk this up to normal four-year-old behavior, this coupled with aggression issues we have been battling are started to make me wonder if he's bipolar as well. How young is too young to seek a diagnosis?