Children whose diet includes fish at least once a week are found to have better sleep and higher IQ scores, on average, than their peers who seldom or never eat fish, according to a new study by US researchers.

Researchers from the US University of Pennsylvania conducted the study on 541 children aged between nine and 11 years old to examine the relationship between omega-3s, the fatty acids in many types of fish, and improved intelligence and better sleep.

The children, consisting of 54 percent boys and 46 percent girls, were surveyed about how often they consumed fish in the past month, while their parents were asked about the children's sleeping quality during night and day time.

The boys and girls were also given IQ tests to examine their verbal and non-verbal skills such as vocabulary and coding.

The researchers found that children who ate fish weekly scored 4.8 points higher on the IQ exams than those who "seldom" or "never" consumed fish.

Even those children who sometimes ate fish could get a score 3.3 points higher, the study said.

The children who included more fish consumption in their diet reported fewer disturbances of sleep and have better overall sleep quality, the study revealed.

"Lack of sleep is associated with antisocial behavior; poor cognition is associated with antisocial behavior," said Adrian Raine, professor of the Penn Integrates Knowledge program of the University of Pennsylvania, who was part of the study.

The findings of the study were published in Scientific Reports of the recent edition of the Nature journal.