The importance of these findings cannot be underestimated, experts say, as poor sleep and sleep disturbances in children are associated with obesity, depressive symptoms, attention deficit hyperactivity disorder and poor neurobehavioral functioning.
 
According to principal investigator Katri Räikkönen, PhD, in the department of psychology at the University of Helsinki, Finland, even low levels of weekly prenatal exposure to alcohol have adverse effects on sleep quantity and quality during childhood.

Results indicate that children exposed prenatally to alcohol were 2.5 times more likely to have short sleep duration and 3.6 times more likely to have low sleep efficiency. Smaller body size at birth also was associated with poorer sleep and with a higher risk for clinically significant sleep disturbances among children born at term. In addition, children with short sleep duration were more likely to have been born via Caesarean section than were children who slept longer.
 
"The results were in accordance with the fetal origins of health and disease hypothesis and the many studies that have shown that adverse fetal environment may have lifelong influences on health and behavior," Räikkönen is quoted as saying. "However, this is among the few studies that have reported associations between birth variables and sleep quality and quantity among an otherwise healthy population of children."

The epidemiologic cohort study obtained data from 289 children born at term (from 37 to 42 weeks of gestation) between March and November 1998. Sleep duration and sleep efficiency (actual sleep time divided by the time in bed) were measured objectively by actigraphy at 8 years of age for an average of 7.1 days. Parents completed the Sleep Disturbance Scale for Children to report sleep problems and sleep disorder symptoms such as bedtime resistance and sleep disordered breathing.

The results demonstrated that among children born healthy and at full-term, a linear relationship exists between smaller body size at birth and poorer sleep quality eight years from birth.