DD is 6+month old, she goes to sleep on her own but wakes in the night for no apparent reason. She doesn't cry just babbles to herself. This can go on for at least 2 hours. She has blackout curtains and is in a sleeping bag. It is now creating problems as I also have a DS who is 2yrs and he is waking up now. I have tried bringing her into bed but she thinks it's playtime. I don't want to give her a bottle as she hasn't had one in the night since 3mths old. Any suggestions on why she could be doing this?