Sleep on your left side. This is the single best sleeping position for heartburn, and the reason comes down to where your stomach sits in your body. When you lie on your left side, your esophagus sits above your stomach, so gravity helps keep acid where it belongs. On your right side, the opposite happens: your stomach ends up above the junction where it connects to your esophagus, and acid flows upward more easily.
Why Your Left Side Works
Your stomach is a curved pouch that sits slightly to the left of your midline. At the top, a muscular valve called the lower esophageal sphincter acts as a gate between the stomach and the esophagus. When you roll onto your left side, that gate sits higher than the pool of acid and food below it. Even if the valve relaxes briefly (which happens naturally during sleep), gravity is working in your favor.
When you lie on your right side, the geometry flips. Your stomach rotates so the acid pool sits above the valve. Any momentary relaxation of that valve now lets acid slide downhill into your esophagus. A systematic review and meta-analysis published in 2023 found that left-side sleeping reduced both the percentage of time the esophagus was exposed to acid and the time it took to clear each reflux episode. The acid exposure difference between left and right was clinically meaningful, with right-side sleepers averaging roughly two percentage points more acid contact time in the esophagus per night.
What Happens on Your Back
Back sleeping isn’t as harmful as right-side sleeping, but it’s not ideal either. When you’re flat on your back, acid can pool around the valve without gravity pulling it away in either direction. People who reflux while sleeping on their backs tend to have longer acid clearance times, meaning each episode of acid in the esophagus lingers. That prolonged contact is what leads to the burning sensation that wakes you up, and over time it can irritate or damage the esophageal lining.
If you strongly prefer sleeping on your back, elevating your upper body can compensate significantly. But if you can train yourself to stay on your left side, that alone does more to reduce reflux episodes than back sleeping with elevation.
Elevate Your Head and Chest
Combining left-side sleeping with head-of-bed elevation gives you the strongest protection against nighttime heartburn. The goal is to raise your entire upper body, not just your head. Propping up extra pillows under your neck can actually kink your body and increase abdominal pressure, making reflux worse.
Clinical trials have consistently used an elevation of about 20 centimeters (roughly 8 inches), with some going up to 28 centimeters (about 11 inches). You can achieve this in two ways:
- Bed risers or blocks: Place them under the two legs at the head of your bed. This creates a gentle, full-body slope so your torso stays aligned. Most studies used wooden blocks or metal cones in the 20 to 28 centimeter range.
- Wedge pillow: A foam wedge that sits under your upper back and head. Most wedge pillows designed for reflux use a 30- to 45-degree angle and raise the head 6 to 12 inches. These are more practical if you share a bed with someone who doesn’t need elevation, or if you can’t modify the bed frame.
Bed risers tilt the entire sleeping surface, which some people find more comfortable because the body stays in a natural line. Wedge pillows are easier to set up and travel with, but some people slide off them during the night. Either option works. The key is that the elevation is gradual and starts at your waist or mid-back, not at your neck.
Timing Your Last Meal
No sleeping position fully compensates for going to bed on a full stomach. Your stomach takes time to break down food and move it into the small intestine, and lying down before that process is well underway means more volume pressing against the valve. The widely recommended buffer is at least three hours between your last meal and lying down. That window gives your stomach enough time to empty the bulk of what you ate while still being short enough that you won’t go to bed hungry.
If you eat a particularly large or fatty meal, you may need even longer. Fat slows stomach emptying, which means the window of vulnerability extends further into the night. On nights when a late dinner is unavoidable, left-side sleeping with elevation becomes especially important.
Heartburn During Pregnancy
Heartburn affects the majority of pregnancies, particularly in the second and third trimesters, as the growing uterus pushes the stomach upward and hormonal changes relax the esophageal valve. Left-side sleeping is the recommended position during pregnancy for reflux management, and it carries the additional benefit of improving blood flow to the uterus and kidneys.
Evidence-based treatment guidelines for reflux during pregnancy list head-of-bed elevation (6 to 11 inches) combined with left-side positioning as a first-line lifestyle measure, alongside avoiding spicy or fatty foods, citrus, carbonated drinks, and not lying down within three hours of eating. These steps are recommended before considering any medication.
How to Stay on Your Left Side
Knowing the best position is one thing. Actually maintaining it through the night is another. Most people shift positions multiple times during sleep, and you may wake up on your right side or back without realizing you rolled over. A few strategies can help.
Place a firm body pillow or regular pillow behind your back to create a physical barrier against rolling. Some people tuck a tennis ball into the back of a sleep shirt to make right-side and back sleeping uncomfortable enough that they unconsciously avoid it. If you use a wedge pillow, positioning it slightly to your left can encourage you to favor that side. Over the course of a few weeks, most people find their body adapts to the new default position.
If you have a condition that makes left-side sleeping uncomfortable, such as a left shoulder injury, elevating the head of the bed and sleeping on your back is the next best option. Right-side sleeping is the position most strongly linked to increased reflux episodes and should be the first one you eliminate.