Eating Omega-3 rich fish is associated with both improved sleep and cognitive ability in school-aged children, say researchers from the University of Pennsylvania.
Writing in Nature’s Scientific Reports, the team report that children who eat fish at least once a week sleep better and have IQ scores that are 4 points higher, on average, than those who consume fish less frequently or not at all.
Led by Jianghong Liu, an associate professor of nursing and public health, the new study goes one step further by suggesting that sleep partially mediated the relationship between fish consumption at age 9–11 years and cognitive ability as measured by IQ at age 12 years. Indeed, the team suggest that sleep quality may be a ‘missing link’ between fish intake and intelligence.
"This area of research is not well-developed. It's emerging," said Liu – noting that the current study looked specifically at Omega-3s coming from food sources and not from supplements.
A missing link?
While the three have never been directly tied together before the current study, research in other areas of study have, for example, highlighted the link between sleep habits, gut microbiome composition and cognitive flexibility in healthy older adults – and a further link between Omega-3 intake and our microbiome make-up.
"Lack of sleep is associated with antisocial behaviour; poor cognition is associated with antisocial behaviour," commented study co-author Professor Adrian Raine. "We have [previously] found that omega-3 supplements reduce antisocial behaviour, so it's not too surprising that fish is behind this."
In the study, a cohort of 541 Chinese children aged between nine and 11 years old (54% boys and 46% girls) completed a questionnaire about how often they consumed fish in the past month, with options ranging from ‘never’ to ‘at least once per week.’
The children also took the Chinese version of an IQ test called the Wechsler Intelligence Scale for Children-Revised, which examines verbal and non-verbal skills such as vocabulary and coding. Parents were also questioned about sleep quality using the standardised Children Sleep Habits Questionnaire, which included topics such as sleep duration and frequency of night waking or daytime sleepiness.
Analysis showed that children who reported eating fish weekly scored 4.8 points higher on the IQ exams than those who said they ‘seldom’ or ‘never’ consumed fish. Those whose meals sometimes included fish scored 3.3 points higher.
In addition, increased fish consumption was associated with fewer disturbances of sleep – which the researchers say indicates better overall sleep quality.
Study co-author Jennifer Pinto-Martin said the findings add to a growing body of evidence that fish consumption has ‘really positive health benefits’ and should be something more heavily promoted.
Given the young age of the study participants, the team chose not to analyse details about the types of fish consumed – but added that they plan to do so for work in older cohorts in the future.
The team also said they want to add to the current observational findings through the use of randomised controlled trials which aim to establish definitive links between eating, sleep quality, and better school performance or other real-life, practical outcomes.
Source: Scientific Reports
Published Online, Open Access, doi: 10.1038/s41598-017-17520-w
“The mediating role of sleep in the fish consumption – cognitive functioning relationship: a cohort study”
Authors: Jianghong Liu, et al