Results indicate preterm infant born to mothers who smoked more than 10 cigarettes per day displayed disrupted sleep structure and sleep continuity, the study said.

The study, published in the journal Sleep, found that newborns slept almost two hours less from 7 p.m. to 8 a.m. than controls who were born to non-smoking mothers. Their sleep was also more fragmented -- newborns born to smokers displayed more body movements and, as a result, more disturbed sleep.

Frederic Telliez of the University of Picardie Jules Verne in Amiens, France, said that sleep integrity is critical in the brain development of newborn children. Disruption of sleep mechanisms by prenatal smoking exposure may predispose these babies to alterations in some physiological function and can result in long-term neurocognitive disorders, Telliez said.

Prenatal smoking exposure can lead to deficits in sustained attention and impulsivity in adolescents and a higher risk of attention-deficit/hyperactivity disorder in childhood -- effects that could be partially mediated by sleep changes, the study said.