Your baby is likely to shake his head back and forth a lot at this point. Earlier he would only do it when he is sleepy but now he shakes his head more frequently even when he is not sleepy. Guess what? Your baby can totally indicate a ''no'' with that head shake!
What you need to know
At this stage, he has been shaking his head when tired for a long time, usually associated with burying his head in your chest or shoulder. He seems to do it when he is happy or just watching the world go by.
Starting from 7 months all the babies do this. It is completely normal. They observe you minutely and start picking up this gesture of yours to say no. You need to understand that it is a very common trait but if you notice some other complications as well, then you should visit a pediatrician.