My daughter is 8 year old. She wakes up (two times) after 15 min. Of sleeping n feels she can't sleep. Again she sleeps nuntill morning. Is it normal.

Sleep Hygiene. http://www.sleepfoundation.org/article/ask-the-expert/sleep-hygiene among other things, don't hover in the room where she is trying to sleep.
Children and Sleep. This question is incomprehensible. Your child 'sleeps until morning'. That sounds pretty normal.