Nina is the same as the 9 mth old girl you mentioned, will happily sit there and watch what is going on. But I have a few friends, who have both girls and boys, and they are full on as well. I don't think it's a hypo, it's just their personality. I have friends staying with us ATM who have a 2.5 yr old, he was always full on, and is definitely full on now. Doesn't mean they'll be this way forever. You're lucky he's sleeping during the day. A girlfriend of mine has a full on 12 month old boy who doesn't sleep whatsoever during the day, but sleeps all night.