Emotions during pregnancy might be to blame as a new study has showed that a mother's prenatal or post natal depression may lead to problems in the sleeping behaviour of her offspring.

The research showed that increased levels of happiness in the second and third trimester were significantly associated with decreased risk for children's sleep problems. "These results promote the caretaking of maternal health and happiness during pregnancy and encourage the roles of familial and community support in aiding expecting mothers," said lead author Jianghong Liu from University of Pennsylvania in the US.

"This will benefit not only maternal health but also the long term behavioural and sleep health of their child," Liu explained. The study, presented during the SLEEP 2018 meeting in Baltimore, included data from 833 kindergarteners with mean age of about six years old. The team also rated the mothers' emotional status, including prenatal/postnatal depressive emotion and perceived happiness throughout trimesters by a self-designed set of questions with a five-point scale for happiness and a three-point scale for depression.

The results showed a significant mediation effect of child's behaviour on the maternal emotion and child sleep relationship as children of the mothers who reported prenatal or post natal depressive emotion, were more likely to exhibit sleep disturbances. "Happiness during the second and third trimester was protective against child sleep problems," Liu said. The results demonstrated that emotion during pregnancy affects child behaviour which further affects child's sleep, Liu explained.