Sleep-wake patterns in preterm infants and 6 month's home environment: implications for early cognitive development.
OBJECTIVE
This study examined the relationship between early organization of sleep-wake states and developmental outcome at 6-month-old premature infants.


METHODS
This was a prospective randomized study that evaluated the sleep-wake states of healthy premature infants in the nursery environment for two successive 72-h periods, at 32 and 36 weeks gestational age.


METHODS
Thirty-four healthy premature infants.


METHODS
Three sleep-wake parameters: percent of quiet sleep, activity level and total amount of sleep, were studied with miniature activity monitors attached to the infant's ankles. The rearing environments of the infants were also assessed at 6 months of age, using the HOME Inventory. Finally, child developmental status was recorded by means of the Mental Development Index (MDI) of the Bayley Scales for Infant Development, at a chronological age of 6 months.


RESULTS
Lower total time spent in night sleep, higher mean level of night activity level, and a later rich home environment were all predictive of higher Bayley scores (MDI) at a chronological age of 6 months. Regression analysis indicated that early biological maturity was more strongly related to the child's developmental status than later home environment, although both contributed to the prediction.


CONCLUSIONS
These results suggest that biological factors may be significant predictors early in development, whereas the impact of environmental influences increases with development.
Meir Medical Center, The Department of Child Development and Neuro-Pediatrics, Kfar-Saba 44281, Israel.
Smadar
S
Gertner
Charles W
CW
Greenbaum
Avi
A
Sadeh
Zipora
Z
Dolfin
Leah
L
Sirota
Yocheved
Y
Ben-Nun
D002657:Child Development; D003071:Cognition; D004777:Environment; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D011446:Prospective Studies; D012044:Regression Analysis; D012890:Sleep; D014851:Wakefulness