Professor Tim Spector, of St Thomas’, said there was evidence that people who snore produce more of a hormone called ghrelin which can increase the appetite and may make them overweight.

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.