Newborn Babies. Full-term, healthy newborns (or infants up to about three months old) should spend the better part of a 24-hour day sleeping. Specifically, they should sleep a total of 14 to 17 hours per 24-hour day. Of course, these hours aren’t consecutive. During the first months of life, a baby will sleep no longer than two to four hours at a time, because of other pressing needs, such as feeding. Typically, a baby should clock eight to 12 hours of sleep at night (with intervals of awakenings for feedings) and accrue the rest by taking two to five naps during the day.