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Newborns display regular cycles of eating, elimination, and states of arousal or degrees of wakefulness. In a typical day, newborns move in and out of five infant states or levels of arousal, as shown in Table 3.2. Most newborns spend about 70% of their time sleeping and wake every 2 to 3 hours. These short stretches of sleep alternate with shorter periods of wakefulness that are primarily devoted to feeding. During the first month, infants often move rapidly from one state to another, dozing off during feeding, for example. Naps are punctuated by periods of drowsiness, alert and unalert activity, and crying.

Table 3.2

Sources: Prechtl (1974) and Wolff (1966).

Newborn sleep cycles are brief, lasting from 45 minutes to 2 to 3 hours, but similar to those of adults in that they consist of both REM sleep, or rapid eye movement sleep, and non-REM sleep (Korotchikova, Stevenson, Livingstone, Ryan, & Boylan, 2016). When a person is in REM sleep, the brain wave activity is remarkably similar to that of the waking state. The eyes move back and forth beneath closed lids; heart rate, blood pressure, and breathing are uneven; and there are slight body movements. It is sleep. Newborns spend about half of their sleep time in REM, but by ages 3 to 5, children spend about 15% to 20% of their sleep in REM, similar to adults (Grigg-Damberger & Wolfe, 2017; Kobayashi, Good, Mamiya, Skinner, & Garcia-Rill, 2004).

Why do newborns spend so much time in REM sleep? REM sleep is associated with dreaming in both children and adults. Neonates spend about 18 hours sleeping each day and therefore spend little time in the active alert state in which they get stimulation from the environment. REM is a way that the brain stimulates itself, which is important for the growth of the central nervous system (Grigg-Damberger & Wolfe, 2017). This view of REM sleep as serving a self-stimulation function is supported by findings that fetuses and preterm babies, who are even less able to take advantage of external stimulation than are newborns, spend even more time in REM sleep. In addition, neonates with low REM sleep activity tend to score lower on mental tests at 6 months of age (Arditi-Babchuk, Feldman, & Eidelman, 2009).