People buy pillows for both and a pillow only addresses one of them, which is why some purchases disappoint.

Where the Pillow Helps

Pain in the neck itself, or across the top of the shoulders into the base of the neck, that is worst on waking and eases through the morning.

That pattern is characteristic of a position held too long: muscles fatigued by supporting a head at the wrong angle for hours.

Correcting the height frequently resolves it within a couple of weeks.

Where It Does Not

• Pain deep in the shoulder joint itself
• Pain when lifting the arm or reaching overhead
• Pain on the side you lie on, which is a pressure problem
• Pain that is present all day and unchanged by sleep
• Anything that started after a specific injury

Where a range describes cutouts as relieving pressure on the shoulder, of the kind at bespillow.net, that addresses the geometry of side sleeping rather than a joint problem inside the shoulder.

The Mattress Is the Other Half

Frequently the actual culprit for shoulder pain in side sleepers.

A mattress too firm does not let the shoulder sink, so body weight concentrates on a small area for hours. That produces exactly the ache people blame on a pillow.

A topper is a cheaper test than a mattress, and it answers the question.

Referred Pain

Worth knowing about. Problems in the neck can produce pain felt in the shoulder or upper arm, because the nerves supplying those areas originate in the cervical spine.

That is why the two get confused, and why an assessment is more useful than guessing.

When to See Somebody

Pain persisting beyond a few weeks, worsening, or waking you regularly warrants a GP or physiotherapist.

Some things need prompt attention rather than experimentation: pain radiating into an arm with numbness, tingling or weakness; pain after a significant injury or fall; inability to move the arm; or neck pain with fever, unexplained weight loss, or problems with balance or coordination.

Daytime Load Matters More

Most people spend far more waking hours with the neck and shoulders under load than they spend asleep.

Screen height, how a bag is carried, and how long you sit still all contribute, and all are free to change.

A Pillow Is Not a Treatment

It holds a position. Language implying more should be read carefully.

Change One Thing

And give it a fortnight before deciding.