Key Takeaways
- Side sleeping is best for most people—especially the left side for acid reflux and pregnancy
- Back sleeping is ideal for spinal alignment but worsens snoring and sleep apnea
- Stomach sleeping is generally the worst position—strains neck and spine
- For back pain, a pillow under the knees (back) or between knees (side) can help dramatically
- Changing positions is hard—but strategic pillow placement can encourage better alignment
We spend roughly a third of our lives asleep, yet most of us never think about how we're positioned during those hours. If you wake up with back pain, neck stiffness, or worse snoring than when you went to bed, your sleep position might be the culprit.
The research is clear: there's no single "best" position for everyone. What's optimal depends on your specific conditions, anatomy, and comfort. But for many common issues—from snoring to sciatica—the science points to clear winners and losers.
01 The Three Sleep Positions
Let's start with an overview of the three main positions and their general pros and cons.
Side Sleeping
~60% of peoplePros
- Reduces snoring and apnea
- Aids digestion (left side)
- Good for pregnancy
- Promotes brain waste clearance
Cons
- Can cause shoulder pain
- May increase facial wrinkles
- Requires proper pillow height
Back Sleeping
~30% of peoplePros
- Best for spinal alignment
- Distributes weight evenly
- Minimizes facial pressure
- Good for most pain types
Cons
- Worsens snoring significantly
- Worst for sleep apnea
- Avoid late in pregnancy
Stomach Sleeping
~10% of peoplePros
- Can reduce snoring
- Some find it comfortable
Cons
- Strains neck (turned to breathe)
- Flattens spinal curve
- Pressure on joints
- Generally not recommended
02 Back Pain
Back pain is one of the most common reasons people seek out position changes. The goal is to maintain the natural curve of your spine while sleeping—something most positions fail at without modification.
Best Position for Back Pain
Back sleeping with a pillow under your knees
This supports the natural lumbar curve and takes pressure off the lower back. A small rolled towel under the small of your back can provide additional support[1].
Good Alternative
Side sleeping with a pillow between your knees
Keeps your hips, pelvis, and spine in better alignment. The pillow prevents your upper leg from pulling your spine out of alignment. Use a firm pillow that fills the gap between your knees.
"The spine has natural curves that need support. When those curves are flattened or exaggerated during sleep, pain results."
— Dr. Michael Breus, Clinical Psychologist & Sleep Specialist
Specific Back Conditions
Lower Back Pain
Best: Back with knees elevated, or fetal position
Avoid stomach sleeping—it hyperextends the lumbar spine.
Sciatica
Best: Side with pillow between knees, affected side up
Takes pressure off the sciatic nerve root.
Herniated Disc
Best: Fetal position (side, curled up)
Opens the space between vertebrae, reducing nerve pressure[2].
Spinal Stenosis
Best: Side sleeping in mild flexion
Flexing forward opens the spinal canal and relieves pressure.
03 Snoring & Sleep Apnea
Position matters enormously for snoring and obstructive sleep apnea. When you lie on your back, gravity pulls the tongue and soft palate backward, narrowing the airway. This is why positional therapy is often the first-line treatment.
Best Position for Snoring/Apnea
Side sleeping (either side)
Keeps the airway open by preventing gravitational collapse of soft tissue. Studies show side sleeping can reduce apnea episodes by 50% or more in positional patients.
Worst Position
Back sleeping
Gravity pulls everything backward—tongue, soft palate, even the jaw. If you snore, avoiding supine sleep is often more effective than anti-snoring gadgets.
Positional Therapy Devices
Can't stay on your side? There are devices designed to train you to stay off your back:
- Tennis ball technique: Sew or tape a tennis ball to the back of your sleep shirt—the discomfort prevents back sleeping
- Positional pillows: Wedge or body pillows that make rolling onto your back difficult
- Wearable devices: Vibrate gently when you roll onto your back, training you without full waking
04 Acid Reflux (GERD)
For acid reflux sufferers, sleep position can mean the difference between a peaceful night and hours of heartburn. This is one area where the research is very clear: the left side wins.
Why Left Side?
The stomach is positioned with the esophageal junction (where food enters) on the right side. When you lie on your left side, gravity keeps stomach contents away from this junction. Lie on your right side and those contents pool right at the entrance to your esophagus[4].
Stomach contents pool away from esophagus. Gravity helps keep acid down.
Stomach contents pool near esophageal sphincter. More reflux episodes.
Elevation Helps Too
In addition to left-side sleeping, elevating the head of your bed by 6-8 inches reduces reflux episodes. This can be done with:
- Bed risers under the headboard legs
- A wedge pillow (not just extra pillows, which bend the body at the waist)
- An adjustable bed frame
05 Pregnancy
Sleep position becomes increasingly important as pregnancy progresses. By the third trimester, the standard advice is clear: sleep on your side, preferably the left.
Best Position for Pregnancy
Left side sleeping ("SOS" - Sleep On Side)
Improves blood flow to the placenta and baby. The inferior vena cava (major vein returning blood to the heart) runs along the right side of the spine—left-side sleeping keeps the heavy uterus from compressing it[5].
Position to Avoid
Back sleeping (after 20 weeks)
The weight of the uterus can compress the vena cava, reducing blood flow. This has been associated with increased risk of stillbirth in some studies, though the absolute risk remains low.
Pregnancy Sleep Tips
- Use a pregnancy pillow: Full-body pillows support your belly and keep you on your side
- Pillow between knees: Reduces hip and back strain from the belly's weight
- Don't panic if you wake up on your back: Your body will usually wake you before harm occurs—just roll back to your side
06 Other Conditions
Neck Pain
Best: Back or side sleeping with proper pillow support
The pillow should keep your head level with your spine—not too high or too low. Avoid stomach sleeping, which requires turning the head 90 degrees.
Shoulder Pain
Best: Back, or on the non-painful side
Avoid sleeping on the affected shoulder. If side sleeping, hug a pillow to prevent the top shoulder from rotating forward.
Hip Pain
Best: Back with pillow under knees, or side with pillow between knees
A mattress topper can reduce pressure points if your bed is too firm. Sleep on the non-painful side if side sleeping.
Sinus Congestion
Best: Elevated head position, or side sleeping
Back sleeping can worsen post-nasal drip. Prop yourself up or sleep on the side with the clearer nostril down.
Heart Conditions
Best: Right side (for some) or elevated
Left-side sleeping can increase awareness of heartbeat and may be uncomfortable with some heart conditions. Consult your cardiologist.
07 Changing Your Sleep Position
Here's the hard truth: changing a sleep position you've used for decades isn't easy. Your body has muscle memory, and you'll naturally revert during sleep. But it is possible with patience and the right setup.
Start Falling Asleep in the New Position
Even if you roll later, starting in the target position helps retrain your body.
Use Strategic Pillows
Body pillows, wedge pillows, or pillows behind your back can block unconscious rolling.
Address Discomfort
If the new position is uncomfortable, you won't stick with it. Invest in the right pillow height and mattress firmness.
Give It Time
Expect 2-4 weeks to form new habits. You may feel more tired initially as your body adjusts.
"Most people move 10-30 times per night. You won't stay in one position all night—focus on starting and returning to the right position."
— Sleep Researchers at Stanford
The Bottom Line
There's no universal "best" sleep position—it depends entirely on what issues you're dealing with. But for most people, side sleeping is the safest default: it's good for your spine, reduces snoring, aids digestion, and is safe during pregnancy.
The worst position for most conditions is stomach sleeping—the neck strain alone makes it worth avoiding. And if you snore or have acid reflux, back sleeping is probably making it worse.
Small modifications—a pillow between the knees, under the knees, or behind the back—can make any position more therapeutic. Experiment with pillow placement, and give your body time to adapt.
Sources & Further Reading
- "Your Pillow May Not Guarantee a Good Night's Sleep or Symptom-Free Waking." Physiotherapy Canada, 63(2), 183-190. (2011) PubMed →
- "Effects of sleeping position on back pain in physically active seniors." Work, 53(4), 851-858. (2016) PubMed →
- "Supine position related obstructive sleep apnea in adults: Pathogenesis and treatment." Sleep Medicine Reviews, 18(1), 7-17. (2014) PubMed →
- "Influence of spontaneous sleep positions on nighttime recumbent reflux." American Journal of Gastroenterology, 94(8), 2069-2073. (1999) PubMed →
- "Association between maternal sleep practices and late stillbirth." EClinicalMedicine, 10, 28-34. (2019) PubMed →
Recommended Resources
- The Sleep Solution by W. Chris Winter, MD
- American Academy of Sleep Medicine: Position Papers
- Sleep Foundation: Best Sleeping Positions
