My baby is 5 months old as well and she sleeps all the time! I think they are growing so fast that they have to sleep to store up enough energy to grow some more. She will get up in the morning with lots of energy and once we take a walk and she eats breakfast, she is out for a couple of hours. Then she wakes up again and wants to play in the afternoon and then takes a nice nap. It works well for me, because I can get stuff done when she is sleeping!
