However, these protective mechanisms become less active during sleep.
As a result, reflux episodes that occur at night may last longer than similar episodes during the day.
A study published in the American Journal of Gastroenterology examined the relationship between sleep position and nighttime reflux in 57 people referred for reflux monitoring.
Researchers found that the left-side position was associated with significantly shorter esophageal acid exposure and faster acid clearance compared with the right-side and back-sleeping positions.
This finding helps explain why left-side sleeping is frequently discussed as a practical measure for people with nighttime heartburn.
3. It may improve sleep quality
Acid reflux does not only affect the digestive system.
It can also interrupt sleep.
Someone experiencing nighttime reflux may wake up because of burning discomfort, coughing, throat irritation, or an unpleasant taste in the mouth.
Repeated interruptions can make it difficult to achieve continuous, restorative sleep.
A study published in the Journal of Clinical Sleep Medicine in 2022 examined the relationship between GERD, sleep quality, and sleeping position.
The researchers found that people with GERD who spent most of their sleep on the right side experienced greater sleep disruption than those who predominantly slept on the left.
The study also found that several negative sleep-quality associations were reduced among participants who primarily slept on their left side.
Although these findings are encouraging, they do not prove that everyone should sleep on the left.
The study involved people with GERD, and individual responses to sleeping positions can differ.
4. What happens when you sleep on the right side after eating?
Imagine eating a large dinner shortly before bedtime.
Your stomach is still processing the meal, producing digestive secretions, and gradually moving its contents toward the small intestine.
If you lie down immediately afterward, you remove much of the assistance normally provided by gravity when standing upright.
For someone susceptible to reflux, this may increase the likelihood of stomach contents moving upward.
Sleeping on the right side may make this situation less favorable than sleeping on the left.
This is one reason digestive specialists often recommend avoiding the right-side position when nighttime reflux is a recurring problem.
However, changing sides cannot completely prevent reflux.
A large meal, obesity, a hiatal hernia, certain medications, and reduced lower esophageal sphincter function can all contribute to symptoms.
5. Is left-side sleeping a treatment for GERD?
It is better understood as a lifestyle measure rather than a complete treatment.
For someone with occasional nighttime heartburn, changing sleeping position may help reduce discomfort.
For someone with persistent GERD, additional measures may be necessary.
These can include dietary adjustments, weight management when appropriate, avoiding late meals, and medication prescribed by a healthcare professional.
The American College of Gastroenterology recommends considering left-side sleeping and elevating the head of the bed for people with nighttime reflux symptoms.
The important distinction is that left-side sleeping may help reduce acid exposure, but it does not switch off the stomach's digestive activity.
It simply changes the physical conditions under which reflux can occur.
For people who regularly wake up with heartburn, this small adjustment may be worth trying.
Chapter 3: What Are the Possible Effects of Sleeping on Your Right Side Every Night?
The warning in the original illustration may sound dramatic, but it is important to understand what medical evidence actually shows.
Sleeping on the right side is not inherently unhealthy.
Millions of people sleep in this position without developing digestive problems.
There is no reliable evidence that simply choosing the right side every night automatically damages the stomach, causes ulcers, or creates cancer.
However, for people who already experience gastroesophageal reflux, this position may make certain symptoms more noticeable.
1. More frequent nighttime heartburn
Heartburn is one of the most recognizable symptoms of acid reflux.
It usually produces a burning sensation behind the breastbone, sometimes extending toward the throat.
The discomfort may become worse after eating, bending forward, or lying down.
When someone sleeps on the right side, stomach contents may be more likely to reach the esophageal opening.
This can contribute to nighttime reflux episodes.
People may notice that symptoms become worse after consuming large meals, fatty foods, chocolate, or alcohol.
However, individual triggers vary.
A food that causes discomfort for one person may have no noticeable effect on another.
2. Acid may remain in the esophagus longer
The duration of acid exposure is important.
The esophagus is protected by several mechanisms, including saliva, swallowing, and muscular contractions.
When reflux occurs while someone is awake, these mechanisms help clear stomach contents.
During sleep, swallowing becomes less frequent and saliva production decreases.
Consequently, nighttime reflux can expose the esophageal lining to acid for longer periods.
Studies comparing sleeping positions have found that acid clearance is generally faster when people with reflux sleep on their left side.
This is one reason left-side sleeping may be particularly useful for individuals who experience symptoms during the night.
3. Reflux may disturb breathing and sleep
Some people with nighttime reflux experience coughing, throat irritation, or a sensation of fluid rising toward the back of the mouth.
These symptoms can interrupt sleep and make it difficult to feel rested the following morning.
In some cases, reflux may occur alongside obstructive sleep apnea.
Sleep apnea is a condition in which breathing repeatedly becomes partially or completely blocked during sleep.
It is important not to confuse the two conditions.
Changing sleeping positions may help certain people with positional sleep apnea, while left-side sleeping may help some individuals with nighttime reflux.
However, neither change should be considered a substitute for proper evaluation and treatment of sleep apnea.
4. Could right-side sleeping damage the stomach?
There is no good evidence that sleeping on the right side directly damages the stomach.
The stomach is a muscular organ designed to contain acidic digestive juices.
Its internal lining has protective mechanisms that help prevent the acid from damaging the tissue.
The main concern with reflux is exposure of the esophagus to stomach contents, not the mere presence of acid inside the stomach.
This distinction is important because online health claims sometimes suggest that right-side sleeping causes stomach acid to destroy internal organs.