School-age children: Weekly fish consumption improves sleep and intelligence test results

Weekly fish consumption may improve sleep quality and enhance cognitive abilities in school-aged children, leading to better intelligence test scores.

According to a new study, children who eat fish at least once a week sleep better and score more than 4 points higher on intelligence quotient tests compared to those who eat fish less frequently. Sleep quality could therefore be one of the connecting factors between omega-3 intake and cognitive performance.

This is reported by a study published by researchers at the University of Pennsylvania (USA) in the journal Nature's Scientific Reports.

Omega-3, cognitive function, and sleep-wake rhythms: is there a link?

Long-chain omega-3 fatty acids are essential nutrients, abundant in fatty fish, with numerous potential health benefits ranging from cardiovascular to mental well-being. Because omega-3s play a fundamental role in the growth and functioning of neural tissue, their effects on cognitive tests are of particular interest to researchers. Fish consumption during pregnancy or supplementation with fish oil, for example, is associated with better neurological development in infants and young children, including language, motor, visual, and coordination skills. A diet rich in seafood is also linked to better cognitive and academic performance in adolescents, as well as reduced cognitive decline and dementia in old age.

While animal studies have demonstrated the role of EPA and DHA in cognitive processes at a molecular level, knowledge about how to improve intellectual performance remains limited. One path yet to be fully explored is sleep and its relationship with cognitive function in adolescents, although it is known that insufficient or poor-quality sleep is associated with poor school performance and reduced learning and memory capabilities. Recent studies show that sleep is influenced by omega-3 fatty acids through various mechanisms.

Some studies have suggested a potential role for DHA in regulating endogenous melatonin production, a substance that regulates the circadian rhythm and improves sleep organization and central nervous system development in infants. Additionally, omega-3s are involved in prostaglandin production, chemicals that act as mediators of inflammation and are believed to be some of the most potent endogenous substances promoting sleep and regulating the sleep-wake cycle. Epidemiological studies have shown significant associations between increased fish consumption and improved sleep in adults, infants, and children. Despite evidence of a relationship between sleep and cognitive abilities, no study has simultaneously examined how a fish- and omega-3-rich diet affects sleep. Most studies on omega-3 dietary intake in school-age children, examining cognitive abilities and sleep, have been conducted almost exclusively in Western countries.

Higher intelligence test scores for children who consume fish

The new study aimed to address these gaps by examining fish consumption, sleep quality, and cognitive outcomes in Chinese children. The goal was to assess whether a fish-rich diet improves sleep and long-term cognitive test results. The research findings showed that children who regularly ate fish at least once a week scored better on intelligence tests, with IQ results nearly five points higher than children who never consumed seafood. Fish consumption was also associated with improved sleep quality. These results suggest that sleep may partly mediate the relationship between fish consumption and cognitive abilities measured by IQ. According to the research team, sleep quality could be the “missing link” between intelligence and omega-3 consumption from dietary sources rather than supplements.

Some study details

In the new study, led by Jianghong Liu, Associate Professor at the University of Pennsylvania, 541 Chinese children (54% boys and 46% girls) aged 9 to 11 completed a questionnaire about how often they had eaten fish in the previous month. The children also took the Chinese version of an IQ test, the Revised Wechsler Intelligence Scale for Children, which assesses verbal and non-verbal abilities. Parents were surveyed about their children’s sleep quality using a standardized questionnaire covering sleep duration, frequency of night awakenings, and daytime fatigue. Analysis showed that children who reported weekly fish consumption scored 4.8 points higher on IQ tests than those who reported eating fish “rarely” or “never.” Those whose meals occasionally included fish scored 3.3 points higher. Increased fish consumption was also associated with fewer sleep disturbances—an indicator of overall better sleep quality.

An innovative study that needs to be expanded

The new research demonstrates for the first time that sleep may act as a mediator between frequent fish consumption and improved intellectual abilities, providing an important mechanism through which a diet rich in EPA and DHA can influence cognitive function. These findings could have significant public health implications for promoting healthy eating habits among children and adolescents. According to co-author Jennifer Pinto-Martin, the research adds to a growing body of evidence demonstrating that fish has “truly positive health benefits” and that its consumption should be encouraged. Due to the young age of the study participants, the team chose not to analyze details about the types of fish consumed, but according to the researcher, the group plans to continue this research by adding details to the current results to establish definitive links between diet, sleep quality, improved school performance, or other practical outcomes.

Source: Jianghong Liu, et al., “The mediating role of sleep in the fish consumption – cognitive functioning relationship: a cohort study”. Nature's Scientific Reports