How long do fifteen to eighteen old babies sleep?

Sleep routine: Many babies will start to waken more often at this age as sleep needs decline. A predictable sleep routine will help as will spending naps and nights in their own bed. Almost all will wake in the night and go back to sleep if we let them. Often sleep is disturbed as a sign of illness, so keep this in mind.

Varies: There appears to be no right answer to how many hours a child sleeps. It is really unique to that child. If they are growing, happy, behaving and developing normally , then whatever amount works for that child. Having said that, most seem to sleep 8-12 hours at night.