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Shoulder MediBilbao Salud

Shoulder Pain From Sleeping on Your Side: Why It Happens and How to Sleep Better

Waking up with a sore shoulder after lying on your side is very common. In some people it is simply the result of hours of pressure on the joint; in others, side sleeping exposes a shoulder problem that was already there, such as irritation of the rotator cuff tendons or bursa. The good news is that small changes in position, pillows and daytime exercise often make a clear difference. This guide explains the causes and gives practical, physiotherapy-based advice.

Topic
Physical therapy
Updated
Reading time
6 minutes
Reviewed by
Dr. Itziar Gotxi Erezuma · Medical doctor (ENT) · Bizkaia Medical Association no. 484809757

Why side sleeping can hurt your shoulder

The shoulder is a shallow ball-and-socket joint held in place mainly by muscles and tendons, especially the rotator cuff. Above the rotator cuff sits a fluid-filled bursa that helps the tendons glide under the bony roof of the shoulder (the acromion). In side sleeping, two things happen:

  • The bottom shoulder is compressed: body weight presses the joint against the mattress and rolls the shoulder blade forwards, narrowing the space for the tendons and bursa.
  • The top arm falls forwards: if it is not supported, it hangs across the chest and pulls the shoulder into an internally rotated position that can pinch the tendons for hours.

Healthy tendons tolerate this well, but tendons that are already irritated or degenerated react with pain, often worse in the early morning. Reduced blood flow from prolonged pressure and stiffness from staying still also contribute.

Shoulder conditions that are worse when lying on the side

  • Rotator cuff tendinopathy or impingement: pain on the outside of the upper arm, worse when lifting the arm to the side or overhead and when lying on it. See supraspinatus tendon injury.
  • Subacromial bursitis: inflammation of the bursa, often together with tendinopathy, with a painful arc of movement.
  • Rotator cuff tear: weakness and night pain, more common after 50 or after a fall.
  • Calcific tendinitis: calcium deposits in the tendon that can cause very sharp pain at night. See calcific tendonitis.
  • Frozen shoulder: gradually increasing pain and stiffness in all directions, typically in people aged 40 to 60 and in people with diabetes. See frozen shoulder.
  • Shoulder osteoarthritis: deep ache and grinding, mostly in older people.
  • Neck problems: a trapped nerve in the neck can cause shoulder and arm pain that is worse in certain positions; see pinched nerve in the shoulder and neck pain from sleeping.

Best sleeping positions for a painful shoulder

  • Sleep on the pain-free side with a pillow hugged against your chest, so the painful top arm rests on it at shoulder height instead of falling forwards.
  • Sleep on your back with a small pillow under the elbow of the painful arm, so the arm is slightly away from your body and supported.
  • Semi-reclined: during a flare-up, some people sleep better propped up on pillows or in a recliner.
  • Avoid sleeping with the arm overhead or tucked under the pillow or your head.
  • If you must lie on the painful side, roll a little towards your back so the weight is on the shoulder blade rather than the point of the shoulder.

Pillows and mattress: what helps

For side sleepers, the pillow should fill the gap between the ear and the mattress so that the neck stays in line with the spine; this is usually a medium-height, fairly firm pillow, and broad-shouldered people need a higher one. A pillow that is too low tilts the head down and pushes more weight onto the lower shoulder.

A mattress that is too firm concentrates pressure on the shoulder, while a very soft one lets the body sink and twist. A medium-firm mattress or a soft topper often reduces shoulder pressure in side sleepers. There is little scientific evidence for any particular brand; comfort and neutral alignment matter most.

What to do during the day

  • Keep the shoulder moving within comfortable limits; complete rest makes stiffness worse.
  • Avoid repeated overhead lifting and reaching behind you while the shoulder is irritable.
  • Do gentle rotator cuff and shoulder blade exercises; see rotator cuff exercises and shoulder external rotation exercises.
  • Improve posture at the desk, with the screen at eye level and the shoulders relaxed.
  • Use ice or heat for 15 minutes before bed, whichever feels better.
  • Simple painkillers taken before bed can help you sleep during a flare-up, if suitable for you.

How a physiotherapist can help

A physiotherapist examines which movements are painful or weak, the position and movement of the shoulder blade, and the neck. Treatment for rotator cuff tendinopathy and bursitis is mainly progressive exercise: strengthening the rotator cuff and shoulder blade muscles, gradually reintroducing overhead movement, and advice on load and sleep. Manual therapy can help short-term pain and movement.

Most people improve within 6 to 12 weeks of consistent exercise. If pain at night remains severe, a doctor may consider a steroid injection to calm the bursa so that exercise becomes possible. Imaging such as ultrasound is useful when a tear is suspected or when the shoulder is not improving.

When to see a doctor

  • You cannot lift your arm after a fall or injury.
  • The shoulder looks deformed or you felt it pop out.
  • Severe pain with a hot, red, swollen shoulder or fever.
  • Pain with breathlessness, chest pain or sweating: call emergency services, as heart pain can spread to the left shoulder.
  • Pain that gets steadily worse at night despite rest, or weight loss without reason.
  • Numbness, tingling or weakness spreading down the arm.

Key points to remember

  • Side sleeping compresses the lower shoulder and can pinch the rotator cuff of the top arm.
  • Persistent pain often points to rotator cuff tendinopathy, bursitis or frozen shoulder.
  • Hugging a pillow, sleeping on the other side or on your back and a suitable pillow height help.
  • Daytime exercise is the main treatment for most shoulder pain that wakes you at night.

Questions about shoulder pain from side sleeping

These answers are general information and do not replace an examination or individual medical advice.

Why does my shoulder hurt after sleeping on my side?

Prolonged pressure compresses the rotator cuff tendons and bursa. If a tendon is already irritated, this causes pain, especially in the morning.

Which side should I sleep on with shoulder pain?

Sleep on the pain-free side with a pillow supporting the painful arm, or on your back with a small pillow under the elbow.

How long does shoulder pain from sleeping wrong last?

Simple positional pain usually settles within a day or two. Pain lasting more than two to three weeks suggests a shoulder condition worth assessing.

Can a pillow cause shoulder pain?

A pillow that is too low or too high changes neck and shoulder alignment and can increase pressure on the lower shoulder.

Is shoulder pain at night a sign of a rotator cuff tear?

It can be, especially with weakness lifting the arm, but night pain is also common with tendinopathy, bursitis and frozen shoulder.

Should I see a physiotherapist or a doctor?

A physiotherapist is a good first step for most shoulder pain. See a doctor first after an injury, with fever or with chest symptoms.

Sources

  1. NHS · Shoulder pain
  2. AAOS OrthoInfo · Shoulder impingement / rotator cuff tendinitis
  3. AAOS OrthoInfo · Rotator cuff tears
  4. NHS · Frozen shoulder
  5. Page MJ, et al. Manual therapy and exercise for rotator cuff disease. Cochrane Database Syst Rev. 2016

This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.