Children sleep significantly better if they are given supplements of fish oil, British researchers have revealed. On average children given fish oil slept an hour longer than others - and they had many fewer incidents of waking up, researchers found. The findings could herald a return to the days when cod liver oil was given daily to children to boost their vitamin levels. Researchers said their study also found that 40% of children aged seven to nine had regular sleep disturbances. Some 362 children took part in the Oxford University study, which compared fish oil with a placebo made from corn oil or soya bean. Researcher Dr Alex Richardson said poor sleep could help explain why deficiency in omega-3, the fatty acid found in fish oil, is also linked to behaviour and learning problems. He said: "Previous studies we have published showed that blood levels of omega-3 DHA in this general population sample of 7-9 year olds were alarmingly low overall, and this could be directly related to the children's behaviour and learning. "Poor sleep could well help to explain some of those associations." The researchers say there is evidence the brain needs omega-3 to help regulate sleep. Their findings are to be published in theJournal of Sleep Research. Fatty acids and sleep in UK children: Subjective and pilot objective sleep results from the DOLAB study – a randomised controlled trial.Journal of Sleep ResearchMarch 2014; doi: 10.1111/jsr.12135