Side sleeping is the best overall sleep position for most people. It keeps your airway open, reduces snoring, and puts less stress on your spine than other positions. But the “best” position also depends on your specific health concerns, whether that’s acid reflux, back pain, pregnancy, or sleep apnea. Here’s what each position does to your body and how to optimize whichever one you choose.
Side Sleeping: The Best Option for Most People
Side sleeping helps prevent your airway from collapsing during sleep, which is why it reduces snoring and improves breathing for people with obstructive sleep apnea. Positional therapy studies show that simply switching from back to side sleeping reduces breathing interruptions by about 7 events per hour on average. That’s a meaningful improvement for mild to moderate cases.
Side sleeping is also the recommended position for neck and back pain, with one important modification: place a pillow between your knees. Without it, the weight of your upper leg pulls on your hip and lower spine all night, which can create new problems. Drawing your legs up slightly toward your chest and keeping a pillow between your knees helps align your spine, pelvis, and hips, taking pressure off your lower back. A full-length body pillow works well if you tend to shift around.
Which side matters, too. Your left side is better for digestion and acid reflux because it positions your esophagus above your stomach, making it harder for stomach acid to flow upward. Sleeping on your right side does the opposite: it places your esophagus below the junction with your stomach, which promotes reflux and slows the time it takes to clear acid. If you deal with heartburn at night, left-side sleeping can make a noticeable difference.
Back Sleeping: Good for Some, Risky for Others
Sleeping on your back has a clear advantage: it distributes your weight evenly and doesn’t put pressure on your joints. For people with shoulder pain, back sleeping produces the lowest pressure inside the shoulder joint compared to side or stomach positions. If you have rotator cuff issues, this position is worth trying.
The downside is significant, though. When you lie on your back, your tongue and jaw can fall backward and crowd your airway. This makes back sleeping the worst position for snoring and sleep apnea. If your partner has told you that you snore loudly or you wake up feeling unrested despite getting enough hours, switching off your back is one of the simplest things you can try.
If you do sleep on your back, place a pillow under your knees. This relaxes your back muscles and preserves the natural curve of your lower spine. A small rolled towel under your waist can add extra lumbar support. Elevating your head slightly may also help reduce snoring, though it won’t fully solve airway obstruction for people with true sleep apnea.
Stomach Sleeping: The Position Worth Changing
Stomach sleeping does one thing well: it keeps your airway open. Beyond that, it creates problems. The biggest issue is your neck. Sleeping face-down forces you to turn your head to one side for hours at a time, making it impossible to keep your cervical spine in a neutral position. This sustained rotation strains neck muscles and can lead to stiffness, headaches, and nerve irritation over time.
Your lower back takes a hit too. Lying prone flattens the natural curve of your lumbar spine and can compress the joints in your lower back, especially if you sleep on a soft mattress that lets your hips sink.
If you’re a committed stomach sleeper and want to transition, a body pillow is one of the most effective tools. Hugging a body pillow while lying on your side mimics the pressure on your chest and stomach that makes prone sleeping feel comfortable. It gives you something to press against without the neck and spine strain. Most people find the adjustment takes a week or two of consistent effort before the new position starts to feel natural.
Sleep Position During Pregnancy
During the second and third trimesters, sleeping on your side is the recommended position. Lying on your back compresses a major blood vessel that carries blood to your uterus, which can make you dizzy and reduce blood flow to your baby. The American College of Obstetricians and Gynecologists specifically recommends side sleeping with one or both knees bent.
Left-side sleeping is ideal in the third trimester because it keeps pressure off internal organs and promotes the best blood flow through the body’s major vessels. Placing a pillow between your knees and another under your belly makes this position more sustainable through the night. Full-length body pillows are popular for a reason: they support your knees, belly, and back simultaneously, reducing the number of times you wake up to rearrange.
How to Actually Change Your Sleep Position
Knowing the best position is one thing. Training your body to stay in it is another. You move unconsciously throughout the night, so the goal isn’t to lock yourself in place. It’s to make your preferred position the most comfortable option so your body returns to it naturally.
Start with your pillow setup. Side sleepers need a thicker pillow to fill the gap between their shoulder and ear, keeping their neck straight. Back sleepers need a thinner pillow that supports the natural curve of the neck without pushing the head forward. Stomach sleepers trying to transition should use the body pillow method described above.
If you’re trying to stop sleeping on your back, the classic tennis ball technique works surprisingly well. Attach a tennis ball (or a similar firm object) to the back of your sleep shirt using a pocket or tape. When you roll onto your back during the night, the discomfort nudges you back to your side without fully waking you. It feels awkward for the first few nights, but most people stop rolling onto their back within two to three weeks and can ditch the ball.
For people who wake up with pain despite using the “right” position, pillow placement is usually the missing piece. A knee pillow for side sleepers, a pillow under the knees for back sleepers, and adequate neck support for everyone. These small additions keep your spine aligned through the night, which is ultimately what determines whether you wake up rested or sore.