We see an increase in overexcitabilities during times of "brain jumps" (times when DD's brain has suddenly seemed to leap from one level of understanding to another, sort of like a growth spurt.)
We also see them when she is stressed about something, and interestingly enough they appear about 3 days before she has been able to figure out what the stress is. So we know that there will be some sort of conversation coming soon about a new stress or worry she has.