Many people have evening routines to help them drift off to sleep—rituals like brushing their teeth or reading for 20 minutes. Most also have a favorite sleep position.

But if you sleep on your side every night—on the same side—you may be at risk for an injured shoulder.

See: Rotator Cuff Injuries

Rotator cuff injuries are typically caused by trauma, tissue degeneration, or shoulder impingement.
Read:
How Do Rotator Cuff Injuries Occur?

What causes rotator cuff injuries?

A group of muscles and tendons stabilize the ball-and-socket joint of the shoulder with a "cuff." These muscles and tendons can be injured from acute causes (a fall or accident) or chronic causes (repetition or overuse).

See: Treating Acute Sports and Exercise Injuries in the First 24 to 72 Hours

If you always sleep on your right or left side, the constant nightly pressure on that shoulder's tendons against underlying bone can cause them to become inflamed or fray. This is known as rotator cuff tendinitis or impingement syndrome.

What Is the Difference Between Tendonitis, Tendinosis, and Tendinopathy?

Symptoms of tendinitis can start with mild pain and stiffness in the shoulder, which you may first notice when you lift your arm or put pressure on your shoulder. Rotator cuff pain is usually felt in the front of the shoulder and stops before the elbow.

See: Rotator Cuff Injuries: Symptoms

Shoulder pain can be treated—sometimes fairly easily

Fortunately, the answer to preventing tendinitis from side-sleeping is easy: You have to switch up your sleep position. If you sleep on your side, keep switching up which side you sleep on. Or you can avoid side-sleeping altogether and sleep on your back.

See: Rotator Cuff Injuries: Initial Treatment

If you are struggling to sleep in a new position, try propping up your pillow higher so there's less pressure on your shoulder.

Switching sleep positions will also help if you're already experiencing pain or stiffness from tendinitis. Resting the affected joint is the answer to treating it, along with icing and immobilizing the joint.

See: The P.R.I.C.E. Protocol Principles

Shoulder pain can also be caused by arthritis, bursitis, nerve problems, or other soft tissue injuries like a shoulder sprain or SLAP tear.

If you're experiencing shoulder pain that continues after a few weeks of self-care, make an appointment with your doctor so you can receive a diagnosis and proper treatment.

See: Rotator Cuff Injuries: Diagnosis

Learn more

Rotator Cuff Injections

3 Causes of Shoulder Instability