SEATTLE—Infants who have difficulty sleeping do not necessarily experience cognitive functioning difficulties, as infants or toddlers, according to research presented at the 23rd Annual Meeting of the Associated Professional Sleep Societies.
“While research continues to discover negative impacts of sleep problems on older children’s daytime behavior and cognitive functioning, relatively little is known about the daytime consequences of such problems in very young children, either concurrently or prospectively,” stated Melissa M. Burnham, PhD, Associate Professor in the Department of Human Development and Family Studies at the University of Nevada in Reno.
The researchers sought to determine whether a relationship existed between waking during the night and sleep-onset difficulties at 9 and 24 months, as well as developmental outcomes at 9 months and 2 years in a large, nationally representative sample (10,000 children; 51% male) from the Early Childhood Longitudinal Study-Birth Cohort. Dr. Burnham and colleagues remarked that most of the existing research has examined relatively small samples. The parents (mainly mothers) completed questionnaires at each collection. The Bayley Short Form–Research Edition (mental and motor subscales) and the Toddler Attachment Sort (TAS-45) were used in the analysis. Night waking difficulty was defined as waking at least three times during the night most of the time, and sleep-onset difficulty was defined as needing help to fall asleep most nights.
Most infants were put to bed while still awake (63%), according to parents’ reports. Difficulty with night waking among infants was reported by 3% of parents, while sleep-onset difficulty was reported by 13%.
Testing for Trends
No significant relationships were found between sleep characteristics and Bayley motor scores either concurrently or prospectively. Higher Bayley scores were noted for infants who regularly needed assistance falling asleep than for those who did not have sleep-onset difficulties. The same trend was observed among those who were put to bed already asleep in comparison with those who were put to bed awake.
“Controlling for 9-month Bayley scores, there was a trend for infants whose parents reported sleep-onset difficulties at 9 months to have higher Bayley mental scores at 24 months,” Dr. Burnham and colleagues stated. Scores were also higher at 24 months for those who had been put to bed already asleep at 9 months.
Logistic regression analysis indicated that infants who woke up three or more times during the night regularly at 9 months were more likely to be rated as securely attached by age 2. “The relationship between 9-month night waking and 24-month attachment security was also surprising,” the researchers noted. “Toddlers who had night waking difficulties at 9 months were also more likely to be rated as securely attached on the TAS-45 at 24 months.”
Further Evaluation Needed
Controlling for maternal depression, socioeconomic status, gender, breastfeeding, and race did not alter the outcomes. The findings show a positive relationship between sleep-onset difficulties and cognitive functioning, and are in contrast to what has been reported previously. Dr. Burnham told Neurology Reviews that although it is premature for the results to be directly relevant to clinicians, they do “warrant caution when issuing blanket statements about very young children’s ‘sleep problems’ and their potential effects.” Both large, nationally representative samples and smaller samples are needed for future research.
“Both types of work will help to elucidate the boundaries of what is considered a ‘sleep problem’ in very young children, and the impact of such ‘problems’ on children’s daytime functioning,” Dr. Burnham commented.
“Our results suggest that sleep difficulties in infancy may need to be reconceptualized and are not as unequivocally detrimental to developmental or relational outcomes as they appear to be in later childhood,” she concluded.
—Laura Sassano