Why does my shoulder hurt at night?

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If you’ve been searching “why does my shoulder hurt at night” or “how to sleep with shoulder pain,” you’re dealing with one of the most common issues we see at Flinders Health and Wellness. Nighttime shoulder pain is typically the primary reason people come and seek treatment. Understanding your shoulder anatomy and why pain worsens at night is the first step to finding relief.

Understanding Shoulder Anatomy and Night Pain

So here is some basic info about the anatomy of the shoulder:

• Your shoulder is a ball-and-socket joint called the glenohumeral joint. The “ball” (humeral head) sits in a shallow socket (glenoid) on your shoulder blade. This joint is surrounded by:

• Rotator cuff: Four muscles and tendons that stabilize your shoulder

• Labrum; A ring of cartilage that deepens the socket and stabilizes the joint

• Bursa: Fluid-filled sacs that cushion the tendons

• Joint capsule: The connective tissue envelope surrounding the joint

When any of these structures become irritated, inflamed, or torn, lying down can increase pressure and compression, making pain significantly worse at night.

Now another thing to be aware of - is not all shoulder pain is true “shoulder pain” - if you are experiencing any pain not improved with changing positions and you are experiencing and reflux, shortness of breath or other issues with your digestive tract - please seek medical attention.

Why Shoulder Pain Gets Worse at Night: The Science

Several mechanical factors increase shoulder stress when you lie down:

Sleeping on your painful shoulder compresses inflamed structures

When you lie directly on an irritated shoulder, your body weight compresses the rotator cuff tendons, labrum, bursa, and joint capsule. This compression aggravates conditions like:

1. Rotator cuff tendinopathy or tears

2. Labral tears (SLAP tears, Bankart lesions)

3. Shoulder impingement syndrome

4. Subacromial bursitis

5. Biceps tendinopathy

Poor pillow support causes impingement

A pillow that’s too flat or a sagging mattress allows your arm to fall into positions that narrow the subacromial space—the area where your rotator cuff tendons pass under the acromion bone. This creates or worsens shoulder impingement and pinches the rotator cuff.

Overhead arm positions increase joint pressure

Sleeping with your arms raised above your head (the starfish position) increases intra-articular pressure in the glenohumeral joint and can compress the brachial plexus nerves. This is especially problematic for people with:

1. Labral tears

2. Shoulder instability

3. Thoracic outlet syndrome

4. Rotator cuff injuries

Reduced blood flow at night

When you’re lying still, blood flow to injured tissues decreases, which can increase pain sensitivity and slow the removal of inflammatory chemicals from damaged rotator cuff tendons or torn labrum tissue.

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Best Sleeping Positions for Shoulder Pain Relief

Back Sleeping for Rotator Cuff and Labral Tear Pain

Sleep on your back with arms at your sides.

This is widely considered the best sleeping position for shoulder pain because it:

- Minimizes direct pressure on the rotator cuff and labrum

- Maintains neutral shoulder alignment

- Reduces impingement in the subacromial space

- Works well for rotator cuff tears, labral tears, and shoulder impingement

Use a pillow under your sore arm

Placing a small pillow or folded towel under your affected arm helps:

- Open the anterior shoulder joint space

- Reduce impingement pain

- Support the humeral head in proper alignment

- Decrease tension on the labrum and rotator cuff

Try a reclined position for severe pain

If flat back sleeping is uncomfortable, sleeping at a 30-45 degree angle using a wedge pillow can reduce glenohumeral joint pressure. This position is particularly helpful for:

- Post-surgical shoulder recovery (rotator cuff repair, labral repair)

- Shoulder arthritis

- Severe rotator cuff tears

- Frozen shoulder (adhesive capsulitis)

Side Sleeping with Shoulder Pain: Labral Tears and Rotator Cuff Injuries

Sleep on your good side (never the painful shoulder)

One of the biggest mistakes people make is sleeping on their painful shoulder. This directly compresses:

- Torn or inflamed rotator cuff tendons

- Damaged labrum tissue

- Inflamed bursa

- The entire glenohumeral joint capsule

This position is especially harmful for labral tears and rotator cuff pathology.

Hug a body pillow to support your top arm

When sleeping on your non-painful side, place a firm pillow in front of you to support your sore arm. This prevents:

- Internal rotation of the glenohumeral joint

- Compression of the labrum

- Rotator cuff impingement

- Your arm from hanging across your body

This setup is critical for people with labral tears, as unsupported positions can stress the damaged cartilage.

Use a pillow behind your back for stability

This prevents unconscious rolling onto your painful shoulder during REM sleep—especially important for:

- Acute rotator cuff tears

- Recent labral tear diagnosis

- Post-operative shoulder recovery

- Shoulder instability

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Common Shoulder Conditions That Cause Night Pain

Rotator Cuff Tears and Tendinopathy

The rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis muscles) is the most common source of nighttime shoulder pain. Partial or full-thickness tears cause pain that’s typically worse at night due to compression when lying down.

Labral Tears (SLAP Tears, Bankart Lesions)

The labrum is the cartilage ring that stabilizes your shoulder socket. Labral tears—including SLAP tears (superior labrum anterior to posterior) and Bankart lesions—cause deep shoulder pain that often worsens at night. Athletes who throw, lift overhead, or have had shoulder dislocations are particularly prone to labral tears.

Shoulder Impingement Syndrome

When the space between your acromion bone and rotator cuff narrows (subacromial impingement), tendons get pinched. This causes pain that intensifies when lying in positions that further narrow this space.

Frozen Shoulder (Adhesive Capsulitis)

The shoulder joint capsule becomes thickened and tight, causing severe nighttime pain and restricted range of motion.

Subacromial Bursitis

Inflammation of the bursa (fluid-filled cushioning sac) between the acromion and rotator cuff causes pain with compression—exactly what happens when you sleep on that shoulder.

AC Joint Arthritis

Arthritis in the acromioclavicular joint (where your collarbone meets your shoulder blade) causes pain that can worsen with certain sleeping positions.

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Worst Sleeping Positions for Shoulder Pain (What to Avoid)

Stomach sleeping: The worst position for rotator cuff and labral injuries

Sleeping on your stomach is the worst position for shoulder pain because it:

- Forces cervical spine rotation

- Pushes arms into overhead or “W” positions

- Creates maximum stress on the rotator cuff and labrum

- Compresses neurovascular structures (thoracic outlet)

- Can aggravate labral tears and shoulder impingement

Starfish position (arms overhead while on back)

Sleeping with your arms raised above your head:

- Increases glenohumeral joint pressure

- Narrows the subacromial space

- Stresses the labrum and rotator cuff

- Compresses the brachial plexus nerves

- Frequently causes nighttime tingling, numbness, or pain

This position is particularly problematic for people with labral tears, shoulder instability, or thoracic outlet syndrome.

Letting your arm hang unsupported

If your painful arm dangles off the bed or gets pinned under your body:

- The humeral head shifts out of optimal position

- Rotator cuff tendons are stretched

- The labrum experiences abnormal stress

- Inflammation worsens

- Morning stiffness and pain increase

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How to Set Up Your Bed for Shoulder Pain Relief

Choose the right pillow for shoulder pain and neck alignment

Your pillow height directly affects shoulder position and stress on the rotator cuff and labrum:

- Side sleepers: Need a thicker, medium-firm pillow (10-15cm) to fill the space between ear and shoulder

- Back sleepers: Need a thinner pillow (6-10 cm) to maintain neutral cervical alignment

- Consider a cervical contour pillow: These maintain proper neck curve and reduce shoulder stress - we have the Complete Sleeperrr available in our clinic.

Use positioning pillows strategically for rotator cuff and labral support

Extra pillows aren’t just for comfort—they’re therapeutic positioning tools:

- Arm support pillow: Place under or beside your painful arm to support the humeral head and reduce rotator cuff/labral stress

- Knee pillow: Maintains hip and spine alignment, preventing compensatory shoulder positions

- Back support pillow: Prevents rolling onto your injured shoulder during deep sleep cycles

Evaluate your mattress for proper shoulder support

Your mattress firmness affects shoulder alignment:

- Too soft: Allows excessive shoulder depression, creating abnormal glenohumeral joint angles

- Too firm: Can create pressure points that worsen pain

- Ideal: Medium-firm mattress that contours slightly while maintaining alignment

Memory foam or hybrid mattresses often work well for people with rotator cuff tears and labral injuries.

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Shoulder Anatomy Deep Dive: Why Structure Matters for Sleep Position

Understanding your shoulder’s complex anatomy helps explain why position matters so much:

The Glenohumeral Joint

This ball-and-socket joint has the greatest range of motion of any joint in your body—but that mobility comes at the cost of stability. The shallow socket (glenoid) provides minimal bony constraint, making the shoulder dependent on soft tissue structures.

The Labrum: Your Shoulder’s Shock Absorber

The labrum is a fibrocartilage ring that:

- Deepens the glenoid socket by up to 50%

- Provides stability during arm movements

- Acts as an attachment point for ligaments and biceps tendon

- Distributes pressure across the joint

When you have a labral tear - whether a SLAP tear (affecting the top of the labrum) or a Bankart lesion (affecting the front) - improper sleeping positions can stress the torn tissue and prevent healing.

The Rotator Cuff: Your Shoulder’s Dynamic Stabilizers

Four muscles form the rotator cuff:

1. Supraspinatus: Initiates arm abduction (most commonly torn)

2. Infraspinatus: External rotation

3. Teres minor: External rotation and adduction

4. Subscapularis: Internal rotation

These tendons pass through the narrow subacromial space. When you sleep in positions that narrow this space, you create impingement that irritates or further damages torn rotator cuff tendons.

The Subacromial Space: Where Impingement Happens

This is the area between your acromion bone (part of the shoulder blade) and the humeral head. The rotator cuff tendons and bursa pass through this space. When you sleep with your arm in certain positions, this space narrows, pinching the rotator cuff - this can also be a result of other injuries to the rotator cuff or the bursa - but sleeping might further compress the space.

When to See a Doctor for Shoulder Pain at Night

While sleep position changes can provide relief, persistent nighttime shoulder pain may indicate serious conditions requiring professional diagnosis and treatment.

Seek immediate medical attention if you experience:

- Sudden, severe shoulder pain after trauma

- Complete inability to move your shoulder

- Obvious deformity or dislocation

- Severe pain with fever (possible infection)

- Numbness/weakness in your entire arm

- Night pain persists beyond 3 days despite position changes

- Morning stiffness lasts more than 30-60 minutes

- Shoulder range of motion is significantly restricted

- You can’t lift your arm overhead

- Pain interferes with work or daily activities

- You have clicking, popping, or catching sensations (may indicate labral tear)

- Your shoulder feels unstable or “loose” (possible labral tear or rotator cuff deficiency)

- You experienced a shoulder dislocation (high risk of labral tear)

- Weakness is getting progressively worse (possible rotator cuff tear progression)

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Treatment Options for Shoulder Pain Beyond Sleep Position at our Clinic

Conservative treatments for rotator cuff and labral injuries (this depending on physical assessment and varies due to underlying diagnosis:

• Dry Needling

• Exercise strengthening for the shoulder blade

• Passive mobilisation

• Techniques to encourage thoracic or mid back mobility

• Postural advice and support

• Kinesiotaping

• If your condition has concerning signs, we will encourage imaging: MRI for conditions in younger people or those with suspicious signs for labral tear. Dynamic ultrasound and x-ray are indicated for significant rotator cuff injuries, acromioclavicular joint injuries or following trauma.

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Quick Relief: What to Do for Shoulder Pain Tonight

If you’re dealing with rotator cuff pain, a labral tear, or shoulder impingement right now and need relief:

1. Avoid the painful side: Sleep on your good shoulder or on your back—never directly on the injured side.

2. Support your arm properly: Use pillows to maintain neutral shoulder alignment and support the humeral head position.

3. Apply ice before bed : 15-20 minutes of ice can reduce inflammation in the rotator cuff, bursa, or around a labral tear.

4. Take anti-inflammatory medication: If approved by your doctor, NSAIDs like ibuprofen can reduce pain and inflammation.

5. Try gentle pendulum exercises: Before bed, lean forward and let your arm hang, then gently swing it in small circles. This can reduce stiffness without stressing the rotator cuff or labrum.

6. Elevate slightly: If you have a rotator cuff tear or frozen shoulder, sleeping slightly elevated (30-45 degrees) may significantly reduce pain.

7. Maintain good posture during the day: Poor daytime posture (rounded shoulders, forward head) increases nighttime shoulder pain by creating chronic impingement.

Key takeaways:

- Avoid sleeping on your painful shoulder

- Support your arm in neutral positions

- Never sleep with arms overhead

- Seek professional evaluation for persistent pain

- Address underlying rotator cuff and labral pathology

If you’ve been struggling with nighttime shoulder pain for more than a few weeks, or if you suspect a rotator cuff tear or labral tear, it’s time to get a proper diagnosis. Early treatment prevents progression and improves outcomes.

This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment of shoulder pain, rotator cuff tears, labral tears, or other orthopedic conditions.​​​​​​​​​​​​​​​​