Exposure to war is known to impact children's physical and mental health. Recent research reveals that war exposure might even affect the developmental outcomes of children who are yet to be conceived. In this study, we sought to extend such prior work by investigating longitudinal associations between pre-conception war exposure and the accompanying maternal emotional distress on child sleep. Israeli mothers, who conceived within a year after the Lebanon war in 2006 (N = 68), were followed until their children reached 10 years of age. At that age, child sleep problems were measured through mother and child reports. Results from analyses of covariances (ANCOVAs) showed that war exposure prior to conception itself did not predict child sleep. However, hierarchical regression analyses showed that higher levels of maternal emotional distress, as a result of pre-conception war exposure, predicted more sleep problems in girls. Further exploratory analyses revealed that these associations showed themselves in both maternal and child reports on various sleep domains. In boys, no evidence was found for associations between maternal emotional distress during wartime and sleep 10 years later. These results indicate that war-related pre-conception stress might have long-term, sex-specific effects on child sleep, though replication with larger samples is needed to corroborate the findings.