Waking up with a sour taste? Night-time acid reflux may be the cause

A regular sour or bitter taste on waking may signal night-time acid reflux, says gastrointestinal surgeon Dr Saurabh Bansal. It happens when stomach contents flow back into the oesophagus, often after eating dinner close to bedtime and lying down soon after. Lying flat removes the help of gravity, and less frequent swallowing during sleep slows clearing of the refluxed material.