How much sleep each person needs is up to the individual and this article can only serve as a guide. If you have a very active child, who does not need much sleep, then that may not be a problem. A newborn usually sleeps between 16 and 19 hours per day. They often wake up every two to three hours to eat. Since hunger will usually wake them up, they will not normally sleep for more than four or five hours at a time.
Some babies sleep more than that, maybe for eight or ten hours at a time.
This is all right, provided the child is normal and healthy. Your doctor or health visitor will tell you what to do if this is the case. Approximately five hours of this will be during the day and the rest at night. The baby may still wake up once or twice every night. If the parents still have to nurse or change the baby at night, they should do it without making the child so excited that it can't go back to sleep.