How to Change a Sleeping Baby's Diaper?. A newborn baby may use eight to 10 diapers per day. It is important that parents change these diapers to help prevent diaper rash. A diaper may occasionally need changing while the baby is sleeping. Most parents may not want to wake a sleeping baby. Luckily, changing a diaper while he is peacefully resting is possible. Being prepared and following a few techniques may enable a parent to change a sleeping baby's diaper without waking him.