A:
Your granddaughter's sleep pattern sounds pretty good. Perhaps you are comparing her with other children you know who get less sleep.
Some children need what may seem like a bit too much sleep. However, you point out that she is developing normally and interacts well with others. That's good to hear. I'm not sure why you only said "language-wise" for her development, though.
I assume your granddaughter's behavior is normal for her age beyond just her language skills. For example, when she is awake, does she act tired? You have not described any daytime sleepiness. And it does not sound like she has any sleep-related breathing problems, like snoring.
You probably know that new babies spend most of their time sleeping – as much as 16 to 20 hours every day. This amount decreases after their first few months of life. How much sleep a child needs is different for each age and each child.
Babies usually can sleep through the night by the time they are 9 to 12 months old, plus as many as two to four hours of naptime during the day. The need for naps tends to go away by the time they are 4 or 5, when they are ready for kindergarten.
If there still is any question in your mind, be sure to check with your granddaughter's pediatrician.
Henry H. Bernstein, D.O., is a senior lecturer in Pediatrics at Harvard Medical School. In addition, he is chief of General Academic Pediatrics at Children's Hospital at Dartmouth and professor of pediatrics at Dartmouth Medical School. He is the former associate chief of General Pediatrics and director of Primary Care at Children's Hospital Boston. 
