Side sleeping is the most common sleep position among adults, and for good reason: it keeps the airway open, it is comfortable for many people with back pain, and it is the position doctors most often suggest during pregnancy. But side sleeping done badly leaves you with a numb arm, a stiff neck or a sore hip. The fix is usually not willpower. It is alignment, the right pillows and a mattress that lets your shoulder and hip sink in. Here is how to get it right.
What good side sleeping alignment looks like
Picture a straight line running from the middle of your head, down your neck and along your spine to your tailbone. When you lie on your side, that line should stay roughly level with the mattress. Two things break it:
- Your head drops or tilts up. A pillow that is too flat lets the head fall toward the mattress; one that is too thick pushes it up. Both strain the neck.
- Your hip and shoulder cannot sink. Your shoulders and hips are the widest parts of your body. If the mattress will not let them press in, the waist sags and the spine curves sideways.
How to sleep on your side, step by step
1. Choose a pillow that fills the gap
The gap between your ear and the outside of your shoulder is the height your pillow needs to fill. Broad-shouldered people need a thicker, firmer pillow; smaller frames need less loft. The pillow should keep your nose in line with the center of your chest. Our guide to the best pillow for side sleepers covers loft and fill options in detail.
2. Bend your knees slightly
A gentle bend at the hips and knees takes pressure off the lower back. Avoid pulling your knees tight to your chest. A deep fetal curl rounds the upper back and can leave you stiff in the morning.
3. Put a pillow between your knees
This is the single most useful change most side sleepers can make. When your top knee drops onto the mattress, it twists the pelvis and pulls on the lower back. A firm pillow between the knees keeps the hips stacked. Some people prefer a longer body pillow they can also hug.
4. Keep your arms in front of you
Tucking your bottom arm under the pillow or your head cuts off circulation and is the usual cause of waking with a tingling hand. Rest both arms in front of your body instead. Hugging a pillow gives the top arm somewhere to go and stops your shoulder rolling forward.
5. Keep your chin neutral
Do not tuck your chin into your chest or tip your head back. A neutral chin keeps the airway open and the neck relaxed.
6. Switch sides occasionally
Spending every night on the same side loads the same shoulder and hip. If you notice soreness on one side, try starting the night on the other.
How to sleep on your side without hurting your shoulder
Shoulder pain is the most common complaint from side sleepers. Usually the cause is one of three things:
- The mattress is too firm. Your shoulder takes the full weight of your upper body instead of sinking in. A softer comfort layer, or a topper, spreads that pressure out.
- You are lying on your arm. Move the bottom arm forward and keep it off the pillow.
- You are rolled too far forward. Lying at a slight backward angle, with a pillow behind your back to lean against, takes weight off the front of the shoulder.
If shoulder pain persists or started after an injury, get it checked by a doctor or physical therapist rather than relying on sleep adjustments alone.
The right mattress for side sleepers
Side sleepers generally do best on a mattress in the soft to medium range, with a comfort layer thick enough for the shoulder and hip to press in while the waist stays supported. Memory foam, latex and hybrids with a generous comfort layer all work well. A very firm innerspring with a thin top usually does not.
- Lighter side sleepers often prefer a softer feel, since they do not compress a mattress as much.
- Average-weight side sleepers usually land at medium.
- Heavier side sleepers often need medium to medium-firm with a thicker comfort layer, so the hips do not sink too far.
In Los Angeles, many side sleepers also run warm. A hybrid, with coils under the comfort layer, tends to sleep cooler than a dense all-foam bed. Browse our mattresses for side sleepers or the soft mattresses for pressure relief collection, and read our guide to the best mattress for side sleepers for specific models.
Is side sleeping right for you?
Side sleeping suits most people, and it is often recommended for snorers because it keeps the tongue and soft tissue from falling back into the airway. It may not be ideal if you already have shoulder problems that are aggravated by lying on them. If you want to try another position, our guide on how to sleep on your back covers the same alignment principles for back sleeping.
Frequently asked questions
Is it better to sleep on your left side?
For some people, yes. Sleeping on the left side is often suggested for people with acid reflux, because it may help keep stomach acid below the esophagus, and doctors commonly recommend side sleeping, often on the left, later in pregnancy. For most healthy people, either side is fine. Choose the side that feels comfortable and does not aggravate any pain.
Why shouldn't you sleep on your right side?
There is no general rule that the right side is harmful. The main reason people avoid it is reflux, since some people find heartburn worse when lying on the right. If you do not have reflux or a specific medical reason to avoid it, sleeping on your right side is generally fine.
Is sleeping on your side bad?
No. Side sleeping is one of the most commonly recommended positions. The problems people associate with it, such as shoulder pain, hip pain and arm numbness, usually come from poor alignment, the wrong pillow height or a mattress that is too firm.
Is it better to sleep on your back or side?
Both can be healthy. Back sleeping distributes weight evenly and is easy on the spine, but it can make snoring and sleep apnea worse. Side sleeping keeps the airway more open and is often more comfortable during pregnancy. The best position is the one you can hold comfortably with your spine in a neutral line.
How do you properly sleep on your side?
Use a pillow tall enough to keep your head level with your spine, bend your knees slightly, place a pillow between your knees, keep your arms in front of you and your chin neutral, and sleep on a mattress soft enough for your shoulder and hip to sink in.
Find a mattress that fits the way you sleep
The quickest way to know whether a mattress works for side sleeping is to lie on it on your side for five minutes and have someone check your spine. You can do exactly that at any of our five Los Angeles showrooms. We offer same-day delivery across the metro and a free 120-night comfort guarantee, so you can adjust if your first choice is not right. Not sure where to begin? Take our sleep quiz for a personalized starting point.
