Sleeping on your left side is the best position for relieving gas and helping it pass through your digestive system. This comes down to anatomy: your stomach and the pathway waste travels through your large intestine are positioned in a way that benefits from left-side gravity. While no single sleeping position will eliminate gas entirely, choosing the left side over the right can make a noticeable difference in overnight comfort.
Why the Left Side Works Best
Your stomach sits naturally on the left side of your body, and it empties into the small intestine from there. When you lie on your left side, gravity helps food and gas move along that natural path rather than fighting against it. Your large intestine follows a specific route as well: waste travels up the right side of your abdomen (the ascending colon), across the middle (the transverse colon), and then down the left side (the descending colon) before reaching the rectum. Lying on your left side lets gravity pull waste and gas downward through the descending colon toward the exit.
There’s also a reflux benefit. The junction between your esophagus and stomach sits slightly to the right of your stomach’s main pouch. When you sleep on your left side, the contents of your stomach sit below that junction, making it harder for acid and gas to creep upward. A 2023 systematic review and meta-analysis found that left-side sleepers had significantly less acid exposure in the esophagus compared to right-side sleepers or back sleepers. One trial in that review found that people who increased their left-side sleeping time experienced more reflux-free nights and improvement in overnight symptoms.
What Happens on Your Right Side
Sleeping on your right side essentially reverses these advantages. Your stomach contents pool near the esophageal opening, which can relax the muscular valve that normally keeps acid and gas contained. This is why right-side sleeping tends to worsen heartburn and the uncomfortable sensation of gas pushing upward. For anyone who already deals with acid reflux or GERD, right-side sleeping can be especially problematic.
The colon layout matters here too. On your right side, gravity works against the natural direction of waste through the descending colon. Gas that would otherwise move toward the rectum can become temporarily trapped, contributing to that bloated, pressurized feeling that wakes you up at night.
Upright vs. Lying Down for Gas
If your gas is severe, it’s worth knowing that body position has a dramatic effect on how quickly gas moves through your intestines. Research published in the journal Gut measured this directly by infusing gas into participants’ intestines and tracking how quickly it cleared. In the upright position, participants retained only 13 milliliters of gas after 60 minutes. Lying on their backs, they retained 146 milliliters over the same period.
The timing gap is just as striking. Upright participants began passing gas about 10 minutes after it entered their system. Supine participants took 17 minutes. During the first 30 minutes, people lying flat retained 47% of the gas volume, while upright participants retained just 23%. Both positions eventually cleared nearly all the gas (97-98% by the end of the study), but being upright sped the process considerably. So if you’re dealing with painful bloating before bed, sitting or standing upright for a while before lying down can help you start the night with less trapped gas.
Elevating Your Upper Body
If left-side sleeping isn’t comfortable for you, or you tend to roll onto your back during the night, elevating your head and torso by about 6 inches can help. A wedge pillow placed under your upper body keeps gravity working in your favor, reducing the chance that gas and acid travel upward toward your esophagus. This is particularly helpful for people who sleep on their backs, since the flat supine position showed no advantage over right-side sleeping in reducing acid exposure.
Stacking regular pillows doesn’t achieve the same effect because they tend to bend your body at the neck rather than lifting your entire torso. A proper wedge, or blocks placed under the head of your bed frame, creates the gradual incline that actually changes how your stomach contents settle.
A Simple Movement Before Bed
One of the easiest ways to release trapped gas before you settle in for the night is the knees-to-chest position. Lie on your back, pull both knees toward your chest, and hold them there for several slow breaths. This gently compresses your abdomen and can help push gas through the intestines. You can do this in bed right before sleep or first thing in the morning when gas often builds up overnight. Rocking gently side to side while holding this position can add a bit of extra movement to get things going.
A Note About Babies
Side-sleeping advice applies to adults only. For infants dealing with gas or reflux, the safest sleep position is always on the back, on a flat and firm surface with no extra bedding or pillows. The American Academy of Pediatrics is clear on this: back sleeping reduces the risk of sudden infant death syndrome (SIDS), and there is no evidence that back-sleeping babies are more likely to choke on spit-up. Devices marketed to elevate a baby’s head in the crib are not effective for reducing reflux and can create dangerous breathing risks if the baby slides into an unsafe position.