There is no single best sleeping position for everyone. The right choice depends on what your body needs: back sleeping keeps your spine and face in neutral alignment, side sleeping is better for snoring and acid reflux, and certain conditions like pregnancy or heart failure call for a specific side. Most people benefit from side sleeping, which is also the most common position, but small adjustments like pillow placement matter just as much as the position itself.
Back Sleeping: Best for Spinal Alignment
Sleeping on your back distributes your weight evenly and keeps your head, neck, and spine in a neutral line. This makes it a strong default for people without specific conditions like sleep apnea or snoring. It’s also the only position that avoids pressing your face into a pillow, which matters for skin health (more on that below).
To get the most out of back sleeping, place a pillow under your knees. This relaxes your lower back muscles and preserves the natural curve of your lumbar spine. If you still feel a gap between your lower back and the mattress, a small rolled towel under your waist can fill it. For shoulder pain, especially a rotator cuff injury, back sleeping is the preferred position. Rest your affected arm across your stomach with the elbow bent and a pillow underneath to lift it slightly, reducing pressure on the joint.
Side Sleeping: Best for Snoring and Reflux
Side sleeping is the most widely recommended position for people who snore or have obstructive sleep apnea. Lying on your back lets gravity pull the tongue and soft tissues toward the airway, partially blocking it. Rolling onto your side opens that airway back up. A meta-analysis of positional therapy studies found that switching from back to side sleeping reduced the number of breathing interruptions per hour by about 54% and improved blood oxygen levels during sleep.
Side sleeping also helps with acid reflux, but which side matters. A study monitoring 57 people with chronic heartburn found that acid backed up into the esophagus at roughly the same rate regardless of position. The difference was how fast it cleared. Acid cleared significantly faster when participants slept on their left side compared to their right side or back. The likely reason is anatomy: the stomach curves to the left, so lying on that side keeps the junction between your stomach and esophagus above the level of stomach acid, letting gravity assist with drainage.
The downside of side sleeping is that it can compress the shoulder you’re lying on and misalign your spine if your pillow setup is wrong. Draw your knees up slightly toward your chest and place a firm pillow between your legs. This keeps your hips, pelvis, and spine aligned and prevents your top leg from pulling your lower back out of position. A full-length body pillow works well if you tend to shift during the night.
Pillow Height for Side Sleepers
Your pillow needs to fill the gap between your ear and the mattress so your neck stays straight rather than bending up or down. For most side sleepers, this means a pillow in the 4 to 5 inch range, though people with narrower shoulders may do fine with 3 inches. A pillow that’s too thin lets your head drop toward the mattress, straining the neck. One that’s too thick pushes your head upward, creating the same problem in reverse.
Left Side vs. Right Side
For most people, left and right side sleeping are interchangeable. But three groups have a clear reason to pick one over the other.
- Pregnant women (second and third trimester): Left-side sleeping allows the most blood flow to the baby. Lying on your back compresses the inferior vena cava, the large vein that returns blood from your lower body to your heart, which can reduce circulation to the placenta.
- People with acid reflux: The left side clears acid faster, as described above.
- People with heart failure: Many prefer the right side. Sleeping on the left can worsen shortness of breath in people whose hearts don’t pump effectively, so they naturally gravitate to the right.
If none of these apply to you, sleep on whichever side feels comfortable. Alternating sides throughout the night is normal and helps prevent sustained pressure on one shoulder or hip.
Stomach Sleeping: The Trade-Offs
Stomach sleeping is generally the least recommended position. It forces your head to turn sharply to one side for hours, straining the cervical spine. It also flattens the natural curve of your lower back, which can lead to stiffness and pain over time.
That said, some people simply cannot fall asleep any other way. If that’s you, place a thin pillow (or no pillow) under your head to minimize neck rotation, and put another pillow under your hips and lower abdomen. This lifts your pelvis enough to reduce the hyperextension in your lower back. Stomach sleeping does have one advantage: like side sleeping, it keeps the airway more open than back sleeping, which can help mild snoring.
Sleeping With Shoulder Pain
Shoulder injuries make sleep frustrating because so many positions put direct pressure on the joint. If you’re a side sleeper, avoid lying on the painful shoulder entirely. Sleep on the opposite side and stack two pillows in front of your chest, with the top pillow supporting your injured arm. This keeps the arm elevated and prevents it from dropping forward, which would internally rotate the shoulder and aggravate the injury.
Back sleeping with the arm supported on a pillow across your stomach is the safest option for rotator cuff problems. The goal is to keep the arm aligned with your body rather than letting it fall to the side or overhead, both of which increase strain on the shoulder joint.
Sleep Position and Facial Wrinkles
Side and stomach sleeping press your face into the pillow for hours each night, subjecting facial skin to shear, compression, and stretching forces that don’t occur when you’re upright. Over years, these repeated mechanical forces contribute to sleep wrinkles, distinct lines that form differently from expression wrinkles caused by smiling or squinting. Research on facial compression during sleep confirms that skin is stretched in multiple directions depending on the position, and this contributes to both wrinkle formation and skin expansion over time.
Back sleeping is the only position that eliminates this facial compression entirely. Silk or satin pillowcases reduce friction but don’t eliminate the compressive forces. For people who prioritize skin health but can’t sleep on their back, these pillowcases are a partial solution at best. Consciously changing a lifelong sleep position is genuinely difficult, and most people revert to their natural position once they fall asleep.
How to Actually Change Your Sleep Position
Knowing the ideal position is one thing. Training your body to stay in it is another. A few strategies that work for most people:
- Pillow barriers: Place pillows along your sides to prevent rolling onto your back (if you’re trying to stay on your side) or wedge them to block rolling onto your stomach.
- Tennis ball method: For people trying to stop back sleeping due to snoring or apnea, sewing a tennis ball into the back of a sleep shirt creates enough discomfort to trigger a position change without fully waking you.
- Wedge pillows: A foam wedge that elevates your upper body 30 to 45 degrees can substitute for side sleeping if reflux is your main concern, keeping acid in the stomach through gravity alone.
- Gradual transition: Start in your target position every night, even if you shift later. Over several weeks, your body spends progressively more time in the new position.
Most people move 10 to 30 times per night, so no one stays locked in one position until morning. The goal is to spend the majority of your sleep in the position that serves your body best, not to achieve perfection.