First sentence is incorrect.. "She is also sleeping" is correct, you use the word "also" when she/he is "also" sleeping at same time as someone else. For example, "His mother is sleeping, and he is also sleeping."

"She is yet sleeping" is not right. Also=the same as. ex. you are nice, but she is also nice. also=as well as. ex. she is singing, but she is also dancing. "She is also sleeping" means that she is sleeping like someone else. Ex. The mother is sleeping. Her daughter is also sleeping. (She is also sleeping= she is sleeping too).

Thank you all of you!

Nobody wants to explain how to fix your first sentence, so I will. :) She is still sleeping.

You first sentence is incorrect.