Because the nervous system of newborns is immature, newborns sleep a great deal, but only for an hour or two at a time, regardless of whether it is day or night. By 4 to 6 weeks of age, many infants are on a cycle of waking for 4 hours and sleeping for 4 hours. By 4 to 6 months of age, infants usually are capable of adopting a day-night sleep schedule. By 1 year of age, most infants sleep 8 to 9 hours continuously through the night. However, disturbances in sleep are common and occur at different times during the first few years (see Sleep Problems in Children Sleep Problems in Children Most children sleep for a stretch of at least 5 hours by age 3 months but then have periods of night waking later in the first years of life, often when they have an illness. As they get older... read more ).
Factors that influence sleep patterns vary by age. At 9 months of age and again around 18 months, disturbances in sleep become common because
Children can move independently and control their environment.
They may take long late-afternoon naps.
They may become overstimulated while playing before bedtime.
Parents can help infants sleep at night by handling and stimulating the child less in the late evening and keeping the child's room dark at night, which is important in the development of normal vision. Infants should be encouraged at an early age to fall asleep on their own and not in a parent's arms. In this way, they will be able to quiet themselves when they wake in the middle of the night Awakening During the Night Most children sleep for a stretch of at least 5 hours by age 3 months but then have periods of night waking later in the first years of life, often when they have an illness. As they get older... read more .
To minimize the risk of sudden infant death syndrome Prevention Sudden infant death syndrome is the sudden, unexpected death, usually during sleep, of a seemingly healthy infant between 1 month and 1 year of age. The cause of sudden infant death syndrome... read more (SIDS), infants should always sleep on their back, rather than on their stomach or in a side sleep position. This recommendation has helped reduce the incidence of SIDS in recent years. Also, infants should not sleep with soft pillows, toys, or heavy blankets, which may block their breathing. Putting an infant to bed with a pacifier may also help prevent SIDS (breastfed infants should be at least 1 month old or accustomed to breastfeeding Breastfeeding Breast milk is the ideal food for newborns and infants. Although babies may be fed breast milk or formula, the World Health Organization (WHO) and American Academy of Pediatrics (AAP) recommend... read more 
before they are given a pacifier). (See also Prevention of SIDS Prevention Sudden infant death syndrome is the sudden, unexpected death, usually during sleep, of a seemingly healthy infant between 1 month and 1 year of age. The cause of sudden infant death syndrome... read more .)
Co-sleeping
Co-sleeping is when a parent and infant sleep close to one another so as to be able to see, hear, and/or touch one another. Co-sleeping arrangements can include
Bed-sharing (the infant sleeps in the same bed as the parent)
Room-sharing (the infant sleeps in a different bed but in the same room as the parent)
Bed-sharing between parents and infants is common but controversial. There are often cultural and personal reasons why parents choose to bed-share, including convenience for feeding, bonding, believing their own watchfulness is the only way to keep their infant safe, and believing that bed-sharing allows them to continue watchfulness even while sleeping. However, bed-sharing has been associated with an increased risk of SIDS and may result in injury or death because infants may become suffocated, strangled, or trapped.
Room-sharing without bed-sharing still allows parents to be physically close to their infant for ease of feeding and monitoring, is safer than bed-sharing or solitary sleeping (the infant sleeps in a separate room), and is associated with a decreased risk of SIDS. For these reasons, doctors recommend room-sharing without bed-sharing as the preferred sleeping arrangement for parents and infants in the first few months of life.
