"This is the first study to evaluate how common heartburn during sleep is in the general population of the USA," said lead researcher Ronnie Fass, from the University of Arizona College of Medicine in Tucson, USA.

To determine the factors that contribute to heartburn during sleep, the researchers sent questionnaires to more than 15,000 people from nine centres across the country. Heartburn during sleep was defined as being woken up two or more times a month by the condition.

The team found that that more than 3800 respondents suffered from heartburn during sleep.

Further analysis of the responses revealed an association between drinking carbonated soft beverages and night-time heartburn. Taking benzodiazepines was also significantly associated with heartburn during sleep. However, the researchers found no evidence of a similar association for antidepressants or calcium channel blocker medications, which have previously been linked to acid reflux.

Other factors that increased the risk of heartburn during sleep included a high body mass index, various sleep abnormalities, hypertension and asthma.

"Heartburn during sleep is indicative of night-time reflux, which has been shown to be associated with a more severe form of gastro-oesophageal reflux disease," said Dr Fass. "Inflammation of the oesophagus, narrowing of the oesophagus, and even cancer of the oesophagus have been associated with night-time reflux."

Commenting on the findings, Dr Paul Kvale, president of the American College of Chest Physicians, said: "There are simple lifestyle changes people can make to help reduce their frequency of heartburn during sleep."

"Reducing consumption of carbonated soft drinks, replacing benzodiazepines with other types of sleeping pills, and losing weight can all help reduce night-time heartburn."

The research is published in the current edition of the journal Chest.