Is this normal I really need to know?!?

My step-mom usually goes to bed around 10pm and wakes up late morning around 10am it's now 4pm 6 hours past here normal wake up time. IS this normal please tell me please my little sister is scared and i just want to asure her that people sometimes sleep that long we are not aloud back in her room please help what should i tell her because i myself am starting to get a little freaked is it normal she never does this? ever