Greater fish consumption is associated with improved cognition among children, but the mediating pathways have not been well delineated. Improved sleep could be a candidate mediator of the fish-cognition relationship.
This study assesses whether 1) more frequent fish consumption is associated with less sleep disturbances and higher IQ scores in schoolchildren, 2) such relationships are not accounted for by social and economic confounds, and 3) sleep quality mediates the fish-IQ relationship. In this cohort study of 541 Chinese schoolchildren, fish consumption and sleep quality were assessed at age 9–11 years, while IQ was assessed at age 12. Frequent fish consumption was related to both fewer sleep problems and higher IQ scores. A dose-response relationship indicated higher IQ scores in children who always (4.80 points) or sometimes (3.31 points) consumed fish, compared to those who rarely ate fish (all p < 0.05). Sleep quality partially mediated the relationship between fish consumption and verbal, but not performance, IQ.
Findings were robust after controlling for multiple sociodemographic covariates. To our knowledge, this is the first study to indicate that frequent fish consumption may help reduce sleep problems (better sleep quality), which may in turn benefit long-term cognitive functioning in children.
Links between sleep problems and low blood levels of the omega-3 found in fish and seafood (EPA and DHA) have already been reported in UK schoolchildren. Furthermore, that study also showed improvements in sleep following supplementation with omega-3 DHA - and the authors suggested that poor sleep might be a mediating factor in the associations between low omega-3 and childhood behaviour and learning difficulties. See:
The current study focused on dietary intake of fish and seafood, not supplementation. It was purely observational, so cannot address possible causal links between omega-3 and sleep - but these findings add to the evidence that this deserves serious investigation.
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