:
"While the average number of hours slept per day at this age is 14, the range of normal is quite wide, with some babies sleeping only 9 hours and others sleeping as much as 18.
The average amount of daytime sleep now is 3-4 hours. Some babies will nap 20 minutes, others will sleep much longer than average."
And from the Pampers Parenting Institute:
:
"The average 4-month-old baby sleeps about nine to 12 hours each day and takes about three two- to three-hour naps each day. This is a time of gradual transition toward two regular daily naps. On days when your baby has just two naps, she'll probably sleep more during the night. Most babies this age have put most of their sleep into the nighttime hours and are more awake during the day."