Newborn babies usually sleep about 16-17 hours in a 24-hour period. Most babies will not sleep through the night until they’re at least 3 months old. There are several reasons why. First of all, their stomachs are very small and they’ll get hungry faster, especially if you’re breastfeeding your baby. Breast milk is much more easily digested than formula, and your baby will need to feed more often, especially in the beginning.
Babies also have shorter sleep cycles than adults do and have shorter dream cycles. In general, though, a newborn baby should sleep about eight or nine hours during the day and eight hours or so at night. These won’t be in eight-hour cycles, of course. In the beginning, those sleep times will be very short.
As the baby gets older, up to about two years of age, she’ll still be sleeping 13-14 hours, but the amount of daytime sleep will diminish month-by-month. By age two, your baby should be sleeping through the night with a two-hour nap during the day. Again, this will vary by child. Your baby might need a slightly longer nap or two short naps. At this age though, try to discourage naps too late in the afternoon, as this can make it harder to get them to sleep a few hours later at bed time.
Once a baby begins to regularly sleep through the night, parents are often dismayed when he/she begins to awaken in the night again. This typically happens at about six months of age and is often a normal part of development called separation anxiety, when a baby does not understand that separations are temporary.