Children who eat fish at least once a week sleep better and have IQ scores that are four points higher, on average, than those who consume fish less frequently or not at all, according to new findings from the University of Pennsylvania published in Scientific Reports, a Nature journal.

Previous studies showed a relationship between omega-3s, the fatty acids in many types of fish, and improved intelligence, as well as omega-3s and better sleep. But they’ve never all been connected before. This work, conducted by the School of Nursing’s  Jianghong Liu, Jennifer Pinto-Martin,  Alexandra Hanlon and Penn Integrates Knowledge Professor Adrian Raine, reveals sleep as a possible mediating pathway, the potential missing link between fish and intelligence.

“This area of research is not well-developed. It’s emerging,” said Dr. Liu, lead author and an associate professor of nursing and public health. “Here we look at omega-3s coming from our food instead of from supplements.”

For the work, a cohort of 541 9- to 11-year-olds in China, 54 percent boys and 46 percent 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.” They 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.

Their parents then answered questions about sleep quality using the standardized Children Sleep Habits Questionnaire, which included topics such as sleep duration and frequency of night waking or daytime sleepiness. The researchers controlled for demographic information, including parental education, occupation and marital status and number of children in the home.    

Analyzing these data points, the Penn team found 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.

“Lack of sleep is associated with antisocial behavior; poor cognition is associated with antisocial behavior,” said Dr. Raine, who has appointments in SAS and Penn’s Perelman School of Medicine. “We have found that omega-3 supplements reduce antisocial behavior, so it’s not too surprising that fish is behind this.”

Dr. Pinto-Martin, who is executive director of Penn’s Center for Public Health Initiatives, as well as the Viola MacInnes/Independence Professor of Nursing and a professor of epidemiology in Penn Medicine, sees strong potential for the implications of this research.

“It adds to the growing body of evidence showing that fish consumption has really positive health benefits and should be something more heavily advertised and promoted,” she said. “Children should be introduced to it early on.” That could be as young as 10 months, as long as the fish has no bones and has been finely chopped, but should start by around age two.