My 7mo sleeps an avg of almost 9 hrs @ night with 2-3 naps during the day. can short sleep damage her brain & hinder her development?

ABSOLUTELY NOT.: You are describing both a normal and healthy sleep pattern for a child of her age. Adequate sleep is absolutely critical for normal neurologic & psychologic development. If your child is seeing a doc regularly, getting her immunizations on time and reaching her appropriate physical and developmental milestones, just be content that you as well have an opportunity to get adequate sleep.