at what age

Would you let your child sleep over a friends house? Sorry I'm torn. My daughter is in 2nd grade. She goes to a catholic school and is 8 yrs old. Her best friend has been asking my daughter if she can sleep over and now I have a note from her best friends mom inviting her over. My daughter had never slept away from home except she has slept at her grandparents house. On one hand I think she will b fine and have a good time. And if something happens I can go pick her up. On the other I feel she may b too young and maybe they can just do Day dates and both go home after. So what do you ladies think? Too young? Give it a try?