Quick Answer: To sleep on your side properly, use a thick pillow (5 to 6 inches) that fills the gap between your shoulder and ear, place a pillow between your knees, and choose a medium to medium-soft mattress that lets your shoulder sink in enough to keep your spine straight. Most shoulder pain from side sleeping comes from a pillow that is too thin or a mattress that is too firm.
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Why Side Sleeping Is the Most Popular Position
About 60 to 70% of adults sleep primarily on their side. There are good reasons for this. Side sleeping opens the airway (reducing snoring), aligns well with the fetal comfort position most of us grew up in, and is the recommended position during pregnancy. The Canadian Chiropractic Association considers side sleeping an acceptable position for spinal health, provided the pillow and mattress support proper alignment.
At Mattress Miracle in Brantford, side sleepers are our most common customer type. After nearly four decades at 441 1/2 West Street, we have noticed that side sleepers have the most specific mattress and pillow needs. A mattress that works well for a back sleeper is often too firm for a side sleeper, and the wrong pillow height is the single most common cause of neck and shoulder pain we see.
Proper Side Sleeping Alignment
When you lie on your side with good alignment, your spine should form a straight horizontal line from your neck to your tailbone. Check this by having someone look at you from behind while you lie on your side on the mattress. Here is what to look for:
Side Sleeping Alignment Checklist
- Head and neck: Your pillow should fill the space between your shoulder and ear completely. Your head should be level, not tilting up or down. If your ear is higher than your shoulder, the pillow is too thick. If it is lower, the pillow is too thin.
- Shoulders: Your bottom shoulder should sink into the mattress enough that it is not taking your full body weight. This is where mattress firmness matters most for side sleepers.
- Hips: Your hips should also sink slightly into the mattress. If the mattress is too firm, your hip pushes your spine into a lateral curve.
- Knees: A pillow between your knees prevents your top leg from pulling your spine out of alignment. This also reduces pressure on the hip joint.
- Arms: Avoid tucking your bottom arm under the pillow. This compresses the shoulder joint and restricts blood flow. Keep your bottom arm extended in front of you or along your side.
How to Sleep on Your Side Without Hurting Your Shoulder
Shoulder pain is the most common complaint from side sleepers, and it usually comes from one of three causes.
Your Mattress Is Too Firm
When the mattress is too firm, your shoulder cannot sink in. Instead, it bears your upper body weight against a hard surface for hours. This compresses the rotator cuff, bursa, and surrounding soft tissue. The fix is a mattress with enough give in the comfort layer to let the shoulder settle in while still supporting the rest of your body. A pillow top or euro top mattress adds the cushioning that side sleepers need at the shoulder.
Your Pillow Is Wrong
A thin pillow forces your head downward, compressing the bottom shoulder further. A thick or stacked pillow pushes your head upward, straining the neck muscles on the opposite side. Side sleepers need the thickest pillows of any sleep position, typically 5 to 6 inches, to properly fill the space between the shoulder and the ear.
You Are Sleeping on the Same Side Every Night
If you exclusively sleep on one side, that shoulder takes all the compression, every night. Try alternating sides. If you have a dominant side you cannot seem to switch from, make sure your pillow and mattress are properly set up for that side.
Shoulder Pain and Sleep Position Research
A study published in the Journal of Physical Therapy Science found that lateral shoulder pressure during sleep significantly increases with mattress firmness. The study recommended that side sleepers use a mattress with adequate pressure point relief at the shoulder and hip to reduce morning pain. The Canadian Physiotherapy Association also notes that pillow height is a modifiable factor in cervical spine strain during side sleeping.
Pillow Setup for Side Sleepers
Side Sleeper Pillow Recommendations
- Head pillow height: 5 to 6 inches for most adults. Broader shoulders need thicker pillows. Measure the distance from the tip of your shoulder to the side of your neck. That is roughly the pillow height you need.
- Head pillow fill: Firm enough to maintain height all night. Shredded memory foam, solid memory foam, or Talalay latex hold their shape. Down and fibre pillows compress overnight, leaving you unsupported by morning.
- Knee pillow: Place between your knees, not below them. A standard pillow works, or use a contour knee pillow designed to stay in place. This keeps your pelvis aligned and reduces hip strain.
- Body pillow (optional): A full-length body pillow supports both the knee position and gives your top arm something to rest on, taking pressure off the bottom shoulder.
At Mattress Miracle, our most popular side-sleeper pillows are the Somnia 4.5 Contour and Somnia 5.5 for larger frames. Both are designed specifically for the height requirements of side sleeping. Browse our full pillow collection to compare options.
Best Mattress for Side Sleepers
Side sleepers need more pressure relief than back or stomach sleepers. Your shoulders and hips are the narrowest contact points with the mattress, and all your weight concentrates there. Here is what works.
Firmness: Medium to medium-soft (4 to 6 on a 10-point scale). Firm mattresses create pressure points at the shoulders and hips. Very soft mattresses lack the support to keep your spine straight.
Material: Memory foam and latex both contour well for side sleepers. Pocket coil mattresses with thick comfort layers (euro top or pillow top) also work well. Avoid thin-comfort-layer innerspring mattresses, which tend to feel hard at the pressure points.
Our picks: The Victoria Plush is specifically designed for sleepers who want softness with support. The Restonic Albany (Plush) offers the same quality coil system as the firm Dalton but with a softer comfort layer. For natural materials, the Elegant Euro Top with latex provides responsive cushioning without the heat retention of memory foam.
Side Sleeper Testing at Mattress Miracle
When side sleepers visit our Brantford showroom, we have them lie on their side for at least five minutes on each mattress. We check shoulder depth (is the shoulder sinking enough?), hip alignment, and whether the spine is level. Bring your own pillow if you have one you like, or try ours. The combination of mattress and pillow matters as much as either one alone. Customers from Brantford, Paris, Hamilton, and the wider GTA make the trip to test properly. Call (519) 770-0001 to check what is on the floor.
Left Side vs Right Side: Does It Matter?
For most people, it does not matter which side you sleep on. But there are a few exceptions.
- Pregnancy: Left side sleeping is recommended because it improves blood flow to the uterus and kidneys. Health Canada and most obstetricians recommend this position in the second and third trimesters.
- Acid reflux (GERD): Research published in the American Journal of Gastroenterology shows that left-side sleeping reduces acid reflux episodes compared to right-side sleeping. The anatomy of the stomach and esophagus favours the left side for reflux management.
- Heart conditions: Some people with heart conditions find left-side sleeping uncomfortable due to the sensation of the heart against the chest wall. If this applies to you, talk to your cardiologist.
- Shoulder injuries: If you have a shoulder injury, sleep on the opposite side. Sleeping on an injured shoulder compresses it further and delays healing.
Medical Disclaimer
The information in this article is for educational purposes only and does not constitute medical advice. If you are experiencing chronic shoulder, neck, or hip pain from sleeping, consult your family doctor, chiropractor, or physiotherapist. They can assess whether your sleep position, mattress, or an underlying condition is the cause.
Frequently Asked Questions
How do I sleep on my side without hurting my shoulder?
Three things: use a mattress that is medium to medium-soft so your shoulder can sink in, use a pillow thick enough (5 to 6 inches) to keep your head level, and avoid tucking your bottom arm under the pillow. A body pillow can help take weight off the bottom shoulder by giving your top arm support. If pain persists, your mattress is likely too firm.
What is the correct way to sleep on your side?
Lie with your spine straight (not curled into a tight ball), pillow filling the gap between your shoulder and ear, knees slightly bent with a pillow between them, and arms in front of you or along your sides. Your head, spine, and hips should form a straight horizontal line when viewed from behind.
Should I put a pillow between my knees when side sleeping?
Yes. A pillow between the knees prevents the top leg from pulling the pelvis out of alignment. This reduces strain on the lower back and hip joints. It is one of the simplest and most effective improvements you can make to your side sleeping setup.
What firmness mattress is best for side sleepers?
Medium to medium-soft, roughly 4 to 6 on a 10-point firmness scale. Side sleepers need the most pressure relief because all their weight concentrates at the shoulder and hip. At Mattress Miracle in Brantford, we recommend testing a plush or euro top mattress and checking that your shoulder sinks in without bottoming out. Call (519) 770-0001 to schedule a visit.
Is side sleeping bad for your back?
Not if your mattress and pillow are properly set up. Side sleeping with proper alignment is considered a healthy sleeping position by the Canadian Chiropractic Association. Problems arise when the mattress is too firm (creating spinal curvature) or the pillow is the wrong height (causing neck strain). With the right setup, side sleeping supports spinal health for most people.
Find the Right Mattress for Side Sleeping
We are a family-owned mattress store in Brantford, helping our community sleep better since 1997. Side sleepers have specific needs, and we know how to match you to the right firmness. Come lie on your side and we will check your alignment.
441 1/2 West Street, Brantford, Ontario
Call 519-770-0001