Chapter 2: Understanding the Digestive System During Sleep
To understand why sleep position matters, it helps to know how the digestive system works.
After food enters the stomach, digestive acids help break it down. Normally, a muscular valve between the stomach and esophagus helps keep stomach contents from flowing backward.
When a person lies down, gravity no longer assists digestion in the same way it does when standing or sitting. As a result, stomach contents may move differently depending on body position.
Some experts suggest that sleeping on the left side may place the stomach in a position that helps keep gastric contents lower than the esophagus. This could potentially reduce the likelihood of acid moving upward during sleep.
On the other hand, some individuals may not notice any difference at all. Factors such as meal timing, food choices, body weight, and overall digestive health often have a much larger influence on comfort than sleeping position alone.