Lifespan Development. Tara L. Kuther

of age and again at 3 to 4 years old showed that lower-quality sleep in infancy was associated with problems with attention and behavioral control in early childhood (Sadeh et al., 2015). Sleep also promotes physical growth and development (Tham, Schneider, & Broekman, 2017).

      Sleeping serves a developmental function, yet young infants wake often. The typical newborn wakes every 2 hours to eat, and babies continue to require nighttime feedings until they are 4 or 5 months old. Cultures differ in infant sleep practices. For example, parents in the United States typically look forward to the time when their infant will sleep through the night, viewing the newborn’s unpredictable sleep pattern as something to fix. In contrast, many European parents view newborn sleep as part of normal development and do not intervene to shape newborn sleep cycles. Children in Pacific-Asian countries tend to sleep an hour less than those in North America, Europe, and Australia (Galland, Taylor, Elder, & Herbison, 2012; Mindell, Sadeh, Wiegand, How, & Goh, 2010). Parental behavior influences infants’ sleep patterns. Infants are more likely to continue waking overnight when their parents play with them during nighttime feedings, as stimulation and attention may reinforce nighttime waking (Sadeh et al., 2015). Cultures also have different practices around sleeping arrangements for infants, toddlers, and older children—including co-sleeping and bedsharing (see Cultural Influences on Development).

      Cultural Influences on Development

      Co-Sleeping

      While sharing a bedroom can enhance the infant–parent bond and make nighttime feedings easier, infants are safest in their own bassinets, such as this one, which is adapted to promote safe parent–infant contact.

      Jennie Hart/Alamy

      The practice of co-sleeping, which refers to the infant sharing a bed with the mother or with both parents, is common in many countries yet controversial in others. In Japan, China, Kenya, Bangladesh, and the Mayan peninsula of Mexico, co-sleeping in infancy and early childhood is the norm and is believed to enhance the child’s sense of security and attachment to the mother (Morelli, Rogoff, Oppenheim, & Goldsmith, 1992; Super & Harkness, 1982; Xiao-na, Hui-shan, Li-jin, & Xi-cheng, 2010). In Latin America and Asia, infants are not usually expected to go to bed and sleep alone at a regular time each night. Instead, they are held until they fall asleep and then are placed in the parental bed (Lozoff, Wolf, & Davis, 1984). In contrast, in many industrialized countries, such as the United States and the United Kingdom, newborns are placed to sleep in their own bassinets, whether in their parents’ room or in a separate nursery. In these countries, learning to sleep by oneself is viewed as fostering independence and the ability to self-regulate (Ball, Hooker, & Kelly, 1999; McKenna & Volpe, 2007). Parents’ decisions of whether to co-sleep are influenced by their own values and beliefs, which are often shaped by the context in which they live.

      Proponents of co-sleeping argue that it best meets the developmental needs of human newborns and aids in forming the attachment bond (McKenna, 2001). Infants who sleep with their mothers synchronize their sleep patterns with hers, permitting more awakenings for breastfeeding, yet lengthening the total time that infants sleep (Gettler & McKenna, 2011). Both mothers and babies benefit from skin-to-skin contact, as it enhances breast milk production, stabilizes infants’ heart rate, increases the prevalence and duration of breastfeeding, and is associated with more positive mother–infant interactions (McKenna & Volpe, 2007; Taylor, Donovan, & Leavitt, 2008). Fathers report that they find co-sleeping rewarding rather than an intrusion on the marital bed (Ball, Hooker, & Kelly, 2000).

      Pediatricians in Western nations tend to advise separate sleeping arrangements for parents and infants. Opponents of co-sleeping point to increased risk of accidental suffocation and an increased risk of SIDS (sudden infant death syndrome), especially among mothers who smoke (Mitchell, 2009). The American Academy of Pediatrics and the United Kingdom Department of Health have declared sharing a bed with an infant to be an unsafe practice; instead, they advise having infants sleep in a crib in the parents’ room (Task Force on Sudden Infant Death Syndrome, 2016; U.K. Department of Health, 2005). Despite these warnings, co-sleeping has become more common among Western families. Some believe that co-sleeping can be safe if appropriate precautions are taken, such as using light bed coverings and a firm mattress and avoiding comforters and pillows (McKenna, 2001). The American Academy of Pediatrics (2016) advises that bedsharing should be abandoned in favor of room sharing, to provide the developmental advantages of co-sleeping and minimize the dangers.

      What Do You Think?

      1 In your view, what are the advantages and disadvantages of co-sleeping?

      2 How might safety concerns of co-sleeping be addressed?

      3 In what ways might parent–child sleeping arrangements influence emotional development?

      Brain development is a multifaceted process that is not is a result of maturational or environmental input alone. Brains do not develop normally in the absence of a basic genetic code or in the absence of essential environmental input. At all points in development, intrinsic and environmental factors interact to support the increasingly complex and elaborate structures and functions of the brain.

      Thinking in Context 4.2

      1 How might contextual factors influence brain development? Consider infants raised in different contexts: urban, suburban, or rural contexts as well as with different family formations, such as single parent, two parent, only child, or multiple siblings. How might these differences influence brain development?

      2 What would you tell a new parent about brain development? Why? What advice might you give new parents on how to promote brain development in their child over the first 3 years of life?

      Early Learning Capacities

      Can newborns learn? If we define learning as changing behavior in response to experience, certainly: Animals and even insects learn. Yet infants were once believed to be born incapable of sensing and understanding the physical world around them. Most new parents will quickly tell you that this is far from the truth. At birth, and even before, neonates can perceive their physical world and have powerful capacities for learning about it.

      Habituation

      Less than 1 day old, cradled next to his mother in the hospital maternity center, Tommy is already displaying the earliest form of learning. He no longer cries each time he hears the loud beep made by the machine that reads his mother’s blood pressure. This type of learning is called habituation; it occurs when repeated exposure to a stimulus results in the gradual decline in the intensity, frequency, or duration of a response (see Figure 4.6). All animals and humans are programmed to learn. Even before birth, humans demonstrate habituation, as early as 22 to 24 weeks’ gestation (Hepper, 2015). For example, 27- to 36-week-old fetuses demonstrate habituation to vibration as well as auditory stimuli, such as the sound of a tone. Initially, the fetus moves in response to the vibration, suggesting interest in a novel stimulus. After repeated stimulation, the fetus no longer responds to the stimulus, indicating that it has habituated to it (McCorry & Hepper, 2007; Muenssinger et al., 2013). Not only can the fetus habituate to stimuli but it can recall a stimulus for at least 24 hours (van Heteren, Boekkooi, Jongsma, & Nijhuis, 2000).

      Figure 4.6 Habituation

      Looking time declines with each trial as the infant habituates to the pattern. Dishabituation, renewed interest, signifies that the infant detects a change in stimulus pattern.