Associations between nocturnal reflux symptoms, use of reflux medications and sleep problems, within a subsample of 786 twins reporting pain behind the breastbone or heartburn.

aNocturnal reflux symptoms was assessed by the question “Have you woken up during the night due to pain behind the breastbone or heartburn?”.bUse of reflux medications was assessed by the question “ Have you taken any of the following medications to prevent pain behind the breastbone or heartburn “, followed by a list of proton pump inhibitors used in Sweden at the time of the data collection.cPearson’s chi-square test measuring the association between nocturnal reflux symptoms and sleep problems.dPearson’s chi-square test measuring the association between use of reflux medications to prevent pain and sleep problems.eThe insomnia index was constructed by combining the three different sleep problem questions and 0 points were given for “seldom”, 1 point for “sometimes” and 2 points for “often”. The highest scores, 4–6 points or if the participant had answered “often”, were then classified as “often having sleep problems”, 1–3 points as “sometimes having sleep problems” and 0 as “seldom having sleep problems”.