London, Aug 3 - Babies exposed to alcohol in the womb and those who are small at birth develop sleep problems as eight-year-olds, says a new study.

Poor sleep and sleep disturbances in children are associated with obesity, depressive symptoms and attention deficit hyperactivity.

Principal investigator Katri Raikkonen, psychologist at the University of Helsinki, Finland, said even low levels of weekly prenatal exposure to alcohol have adverse effects on sleep quantity and quality during childhood.

Children exposed to alcohol in the womb were 2.5 times more likely to have a short sleep duration of 7.7 hours or less and 3.6 times more likely to have a low sleep efficiency of 77.