This is an important distinction. The study did not simply show that people experienced fewer reflux events. It also suggested that when acid entered the esophagus, the body cleared it more quickly while participants were lying on their left side.
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A systematic review and meta-analysis published in 2023 also examined the available research. It found that left-side sleeping was associated with reduced nighttime acid exposure and shorter acid clearance times compared with right-side and back sleeping in people with GERD. The authors noted that the evidence base was still limited and that further research would be useful.
These findings help explain why medical guidance often includes left-side sleeping as one possible lifestyle adjustment for people with nighttime reflux.
Why faster acid clearance matters
The esophagus is not designed to hold stomach acid. When reflux occurs, the body has several protective mechanisms, including swallowing and the movement of saliva, which help clear acidic material.
If acid remains in contact with the esophageal lining for longer, it may cause more irritation. Repeated exposure can contribute to inflammation and, in some people, complications associated with GERD.
A position that helps acid clear more quickly may therefore reduce the amount of time the esophagus is exposed to stomach contents.
However, this does not mean sleeping on the left side cures GERD or repairs existing damage. It is a supportive measure that may reduce symptoms in some people.
Does everyone need to change their sleeping position?
No. If you sleep comfortably on your right side and rarely experience heartburn, there is generally no reason to become anxious about your usual position.
The evidence is most useful for people who experience reflux after lying down, wake up with heartburn, or have been diagnosed with nighttime GERD.
For those individuals, experimenting with the left-side position may be a simple, low-cost adjustment. It can be combined with other habits, such as avoiding large meals close to bedtime and raising the upper body when recommended.
The goal is not to create fear about sleeping on the right. It is to understand that a small change in posture may make a meaningful difference for people whose digestive symptoms interfere with sleep.
Chapter 3: What May Happen If You Regularly Sleep on Your Right Side?
The image uses a warning-style headline to draw attention to right-side sleeping. But the medical evidence needs to be interpreted carefully. Sleeping on the right side is not inherently dangerous, and it does not mean a person will develop stomach disease simply because they prefer that position.
The concern is more specific: in people who are prone to acid reflux, lying on the right side may make nighttime reflux worse compared with lying on the left.
1. Stomach contents may move toward the esophagus more easily
When someone lies down, gravity no longer helps keep stomach contents in the same way it does when standing or sitting. The position of the stomach relative to the esophagus becomes more important.
For some people with reflux, lying on the right side may place the stomach contents in a position that makes it easier for them to reach the lower esophageal sphincter. If that muscular valve relaxes, acid and other stomach contents may move upward.
This does not happen every time someone sleeps on the right. The likelihood depends on several factors, including how much food is in the stomach, whether the person has GERD, how well the lower esophageal sphincter functions, and whether other risk factors are present.
2. Acid may remain in the esophagus longer
One of the findings from research on sleeping positions is that the time needed to clear acid from the esophagus can differ between the left and right sides.
The 2022 study involving 57 people found that acid clearance was significantly faster in the left-side position than in the right-side position. This suggests that the right-side position may allow acid exposure to last longer in some people with nighttime reflux.
Longer exposure can contribute to discomfort and irritation. People may notice burning behind the breastbone, a sour taste, or a sensation that liquid is coming back into the throat.
However, these symptoms are not proof that someone has GERD. Chest discomfort, coughing, and throat irritation can have other causes and should be assessed when persistent or unexplained.
3. Heartburn may interrupt sleep
Nighttime heartburn can make it difficult to fall asleep or remain asleep. A person may wake up, change position, drink water, or sit upright to ease the discomfort.
Repeated sleep interruptions can affect daytime energy, concentration, mood, and general quality of life. For someone who already has reflux, reducing nighttime symptoms may therefore improve more than just digestive comfort.
Changing to the left-side position is one possible adjustment, but it is not the only one. Meal timing, the size of evening meals, alcohol consumption, body weight, smoking, and certain medications can also influence reflux symptoms.
4. Reflux may cause symptoms beyond a burning sensation
Some people associate acid reflux only with heartburn. In reality, GERD can produce several different symptoms.
Common symptoms include:
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A burning feeling behind the breastbone.
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Sour or bitter fluid coming back into the mouth.
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Regurgitation after lying down.
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Discomfort after large or fatty meals.
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Difficulty sleeping because of nighttime symptoms.
Some people also report throat irritation, hoarseness, or coughing. These symptoms are not specific to reflux, however, and other conditions may need to be considered.
5. Repeated reflux deserves attention
Occasional heartburn after a heavy meal does not necessarily indicate a serious health problem. But symptoms that happen frequently, disturb sleep, or require repeated use of over-the-counter medication should not be ignored.