Neonates spend about 17 hours out of 24 in sleep. This sleep time decreases to 14 or 15 hours by the fourth month, where it remains through the eighth month with a very gradual decline, thereafter. Sleep typically predominates during the day in newborns, with a gradual day to night inversion within the first 3 months after birth. However, some newborns may sleep through the night almost immediately. Even though an infant is sleeping through the night, there may be an unexpected regression back to day sleeping from 6 to 12 months due to social/environmental factors which begin to play a regulatory role in sleep.

In 15-20% of infants/toddlers from 6 months to 3 years old, the ability to fall asleep is linked to a set of specific conditions, i.e. being nursed, rocked, held or rubbed by the caretaker, sucking on a pacifier or using a bottle. By the age of 3 or 4, these earlier associations with falling asleep either disappear or are replaced by other bedtime rituals -- usually story reading.

The sleep state in neonates consists of two basic types of sleep: Quiet (precursor to NREM) sleep and Active (precursor to REM) sleep. The Active (REM) sleep percentage for neonates immediately after birth can be as high as 80% dropping down to 30% within the first year. REM sleep cycles every 50-60 minutes in the neonate. Between the 3rd and 5th months after birth, sleep spindles -- the only unique Sleep EEG wave pattern -- are fully developed. And by the end of the first year, the NREM spindle and delta sleep stages are fully appreciated.

Sources: Williams, R.L., Karacan, I., Hursch, C.J. (1974). EEG of Human Sleep: Clinical Applications, Chap. 4 - Normal sleep, pp 29-33. ICSD (1990) - International classification of sleep disorders: Diagnostic and coding manual. Diagnostic Classification Steering Committee, Thorpy MJ, Chairman. Rochester, Minnesota: American Sleep Disorders Association. pp 90-98. American Sleep Disorders Association (1997). ICSD - International classification of sleep disorders, revised: Diagnostic and coding manual. Rochester, Minnesota: American Sleep Disorders Association, pp 90-98.

NEONATES | TODDLERS | CHILDREN | TEENS | ADULTS & SENIORS

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