A recently published report suggesting that the childhood obesity problem is exacerbated by poor sleep says that children who do not get enough sleep at 30 months are likely to be obese at the age of seven. Today’s children have Game Boys, TV sets, mobile phones and 24-hour Internet access to keep then up. They sleep less, and, fatter than ever before.

The same can be said for adults. A study of 1.1 million adults in the US found that those who slept less ended up fatter than those who slept well at night. “The evidence for a link between sleep and obesity is so persuasive”, says a researcher, “that researchers in the States are conducting a trial to see whether extending people’s sleep can help them lose weight.”

He believes that one reason why the genes, which disrupt sleep, may have persisted through the ages is because they make it easier for us to survive in times of intense cold or when food is scarce.

“Poor sleep patterns make people gain weight and retain fat,” he said. “These genes may have helped our ancestors through periods of famine and the Ice Age.”

The findings are published in Twin Research.