I agree sleep talk has an immensely positive impact on the child

Try talking to him when he is deep asleep. Frame positive sentences without using No, don't, never etc. Say what you visualize him doing instead.

How old is ur child? agree with preetjyot. If u cut his nails, he won't have anything to bite on.

How old is your child Kiran... To avoid it for my girl I make sure I cut her nail often avoided it to be long nought for her to bite... Also I told her if she bites germ will come in her mouth and will have a party in her tummy... So whenever she puts her hands in the mouth to bite. She immediately runs to the washroom to wash her mouth...thankfully it till me very little time to stop her from doing this ...