Infant sleep training

During the first year of life, infants spend most of their time in the sleeping state. Assessment of sleep during infancy presents an opportunity to study the impact of sleep on the maturation of the central nervous system (CNS), overall functioning, and future cognitive, psychomotor, and temperament development. Sleep is essential to human life and involves both physiologic and behavioral processes. Sleep is now understood as not simply a resting state, but a state that involves intense brain activity.[1] The first year of life is a time of substantial change in the development of both the human brain and sleep. However, an infant goes through several sleep regressions starting at 1 week, which can occur weekly or fortnightly, until 8 years of age.

The relationship between the two is vital, as the control of sleep and the sleep-wake cycle are regulated by the CNS.[2]

The long sustained sleep period (LSP) is the period of time that a child sleeps without awaking. The length of this period increases dramatically between the first and second months. Between the ages of three and twenty-one months, LSP plateaus, increasing on average only about 30 minutes.[3] In contrast, a child's longest self-regulated sleep period (LSRSP) is the period of time where a child, without sleep problems, is able to self-initiate sleep without parental intervention upon waking.[3] This self-regulation, also called self-soothing, allows the child to consistently use these skills during the nocturnal period. LSRSP dramatically increases in length over the first four months, plateaus, and then steadily increases at nine months. By about six months, most infants can sleep eight hours or more at night uninterrupted or without parental intervention upon awaking.[3]

In terms of actual numbers, an infant from one to three months of age may sleep sixteen to eighteen hours a day in periods that last from three to four hours. By three months the period of sleep lengthens to about four or five hours, with a decrease in the total sleep time to about fourteen or fifteen hours. At three months, they also start to sleep when it is dark and wake when it is light. By four months there are two distinct napping periods: mid-morning and late afternoon. By six months the longest LSP is six hours and occurs during the night. There are two three-or-more hour naps with a total average sleep time of fourteen hours.[4]

Though sleep is a primarily biological process, it can be treated as a behavior. This means that it can be altered and managed through practice and can be learned by the child. Healthy sleep habits can be established during the first four months to lay a foundation for healthy sleep. These habits typically include sleeping in a crib (instead of a car seat, stroller, or swing), being put down to sleep drowsy but awake, and avoiding negative sleep associations, such as nursing to sleep or using a pacifier to fall asleep, which may be hard to break in the future.[4]

Every child is different and each child's sleep becomes regular at different ages within a particular range. In the first few months of life, each time the baby is laid down for bed and each time he or she awakens is an opportunity for the infant to learn sleep self-initiation and to fall asleep without excessive external help from their caregiver. Experts say that the ideal bedtime for an infant falls between 6 pm and 8 pm, with the ideal wake-up time falling between 6 am and 7 am. At four months of age, infants typically take hour naps two to three times a day, with the third nap dropped by about nine months. By one year of age, the amount of sleep that most infants get nightly approximates to that of adults.[4]

Many parents try to understand, once the baby is asleep, how to keep them sleeping through the night. It is thought that it is important to have structure in the way a child is put to sleep so that he or she can establish good sleeping patterns.[4] Dr Sylvia Bell of Johns Hopkins University reported:[5] by the end of the first year individual differences in crying reflect the history of maternal responsiveness rather than constitutional differences in infant irritability. She also notes: consistency and promptness of maternal response is associated with decline in frequency and duration of infant crying. The sleep position is also important to prevent SIDS (Sudden Infant Death Syndrome).[6]

A key debate in sleep training revolves around getting the right balance between parental soothing and teaching the baby to self-soothe. Parents who practice attachment parenting think the parent should attend to the baby whenever he or she cries, and limit tears as much as possible.[7]However, many popular sleep training methods, such as the Ferber Method, rely on letting the baby "cry it out" for a certain number of minutes, so that so-called "self-soothing" skills are fostered instead of an over-reliance upon externally-provided soothing. The Ferber method has been criticized by some for being cruel. Sleep scientists, some of whom profit from sleep training clinics, study isolated variables using "intent to treat" methodologies that leave one uncertain as to what participating families did, have not designed studies that look at child wellbeing variables nor lifelong effects.[8] However, some psychologists say the sleep scientists are failing to take into account the subtle psychological effects of being left alone to cry yourself out; they say: "The fact is that caregivers who habitually respond to the needs of the baby before the baby gets distressed, preventing crying, are more likely to have children who are independent than the opposite. Soothing care is best from the outset. Once patterns of distress get established, it's much harder to change them."[9] Developmental psychological research has demonstrated that emphasizing baby independence in the first year of life is correlated with insecure attachment, which leads to poor peer relations and more dependence later in childhood.[10][11]

Baby soothing techniques include bouncing, jiggling, rocking baby while sitting in a rocking chair, doing knee bends while holding them, doing comfort feeding, providing them with a pacifier, using a white noise machine or app, swaddling them, skin-to-skin contact, using a bouncer or swing to mechanically rock them, and more. Some parents reject the use of most or all baby soothing techniques under the idea that you should teach a baby to self-soothe. Other parents think having devices such as white noise machines and swings are crucial because they allow the parents to take breaks and get things done other than just holding their baby.

Another method is Behavioral Infant Sleep Intervention to effectively reduce infant sleep problems and associated maternal depression in the short- to medium-terms. This method randomized tried and found effective though, despite their effectiveness, theoretical concerns persist about long-term harm on children's emotional development, stress regulation, mental health, and the child-parent relationship.[12] This method proves to be causing no long-lasting harms or benefits to child, child-parent, or maternal outcomes. Parents and health professionals can feel comfortable about using these techniques to reduce the population burden of infant sleep problems and maternal depression.

A number of factors have been shown to be associated with problems in sleep consolidation, including a child's temperament, the degree to which s/he is breast-fed vs. bottle-fed, and his/her activities and sleepiness during the day. Moreover, co-sleeping, which is defined here as sharing a room or bed with parents or siblings in response to an awakening, can be detrimental to sleep consolidation. It is important to note that none of these factors have been directly shown to cause children's sleep consolidation issues.

In terms of infant feeding, breastfeeding has been found to be associated with more waking at night than bottle-fed infants because of the infant's ability to digest breast milk more quickly than formula. Thus, breast-fed infants have been observed to begin sleeping through the night at a later age than bottle-fed infants: bottle fed infants tend to begin sleeping through the night between 6–8 weeks, while breastfed infants may take until 17 weeks before sleeping through the night. Seventeen weeks of age is still within the first 4–5 months of the infants’ life; therefore, this cannot really be considered a delay in sleep consolidation. There are many benefits to breastfeeding infants. Lastly, temperament also seems to yield correlations with sleep patterns. Researchers believe that infants classified as “difficult,” as well as those who are very sensitive to changes in the environment, tend to have a harder time sleeping through the night. Parents whose infants sleep through the night generally rate their infant's temperaments more favorably than parents whose infant continue to wake; however, it is hard to determine if a given temperament causes sleep problems or if sleep problems promote specific temperaments or behaviors.sleepbaby.org

• The Ferber Method