Shoulder pain when sleeping: why it appears at night and what to change
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Quick answer
If your shoulder hurts at night and you sleep on your side, there are two things you can change this very week: the height of your pillow and the mattress's ability to let your shoulder sink in. A mattress that is too firm pushes your shoulder up and misaligns your neck; a low pillow does exactly the same. If the pain wakes you up several nights in a row for weeks, or you can't lift your arm, a bed won't fix it anymore: you need to see an orthopedic specialist or a physical therapist.
In this guide
- Why your shoulder hurts just as you lie down
- The most common causes, and how to identify yours
- Posture: what to change tonight
- The pillow is the piece that makes the biggest difference
- Why a mattress that is too firm makes shoulder pain worse
- Which setup is right for you
- When to stop trying things at home
- Frequently asked questions
Why your shoulder hurts just as you lie down
It's striking that a shoulder that gets through the day without complaining becomes a problem as soon as you turn off the light. It's no coincidence, and there are three reasons that add up.
The first is mechanical. The shoulder is the joint with the greatest range of motion in the body and, in exchange for that mobility, has little bony support: what keeps it in place is mostly muscle and tendon. When you lie on your side, all the weight of your torso rests on a very small surface, the tip of your shoulder. During the day, your legs and spine share that weight; at night, it's concentrated on a joint that isn't designed to support it.
The second is space. Between the bone at the top of the shoulder and the tendons that pass underneath, there is a narrow gap. Certain positions make it even smaller: sleeping with your arm above your head, your hand under the pillow, or your arm hanging forward. If a tendon is already irritated, that compression held for hours is exactly what wakes it up.
The third is that at night, there's nothing else. During the day you move, you get distracted, you change positions without thinking. In bed you are still and silent, and a discomfort you didn't even notice at five in the afternoon becomes the only thing you think about.
An important clarification
This article helps you understand what role your sleep setup plays in shoulder pain, and to correct what depends on it. It is not a diagnosis. At Morfeo, we make mattresses, we are not healthcare professionals, and persistent pain must be assessed by someone who can examine you.
The most common causes, and how to identify yours
Most nighttime shoulder pain falls into one of these categories. The column on the right tells you if changing your sleep setup will help you or if it will only relieve the symptom.
| What it could be | How it is usually identified | Will changing the bed help? |
|---|---|---|
| Posture and sleep setup | The shoulder you sleep on hurts, it improves when you get up and move, and it disappears for a few days if you sleep in another bed | Yes, it is the direct cause |
| Rotator cuff tendonitis | It hurts when lifting your arm from the side, and it gets worse at night even if you don't rest that shoulder | It helps you sleep, but it needs to be treated |
| Frozen shoulder | The shoulder has been losing mobility for weeks or months; it is even difficult to move with the other hand | No. It requires assessment |
| Pain coming from the neck | It is accompanied by tingling or weakness that goes down the arm to the hand | No. It requires assessment |
| Tension and bruxism | It is accompanied by a tight neck and trapezius muscles, and it gets worse during times of stress | It helps, along with other measures |
There is a home test that is quite telling: sleep on the other side for three or four nights. If the pain clearly decreases, the problem is support and setup. If it hurts just as much, or if the shoulder you are no longer resting on hurts, the problem is in the shoulder and the bed only affects how badly you have it at night.
Posture: what to change tonight
This is free and you will notice it quickly. In order of impact:
- Take your arm out from under the pillow and from above your head. It is the gesture that most compresses the gap through which the tendons pass, and many people sleep like this without realizing it. If you find yourself in that position when you wake up, that is your first change.
- If you sleep on your side, hug a pillow. Putting a pillow in front of your chest and resting your top arm on it prevents that arm from falling forward and pulling the shoulder. It is the trick that people who sleep on their side appreciate the most.
- Move the bottom shoulder forward slightly. Instead of resting right on the tip of your shoulder, slide it forward a bit to rest more on the fleshy part of your back. You spread the weight over a larger surface.
- Try sleeping on your back with your arms at your sides. It is the position that puts the least strain on the shoulder, although not everyone manages to sleep like this. If you try it, lower the pillow: when you are on your back, you need much less height than when you are on your side.
- Avoid sleeping on your stomach. It forces you to turn your head all night and usually leaves one arm in a forced position. If it is the only way you can sleep, at least use a very thin pillow or none at all.
Cervical and shoulder pain are often confused because they share muscles. If you notice that the strain starts at the back of your neck and goes down to the trapezius, that article covers it in more detail.
The pillow is the piece that makes the biggest difference
If you are only going to change one thing, let it be this. The pillow is not there to support your head: it is there to fill the gap between the mattress and your head, so that your neck is in line with your spine.
That gap depends on your posture, and that is the key to the shoulder. When you sleep on your side, the gap is the distance between your shoulder and your ear, which is quite large. If the pillow is too low, your head falls toward the mattress, your neck bends, and all the weight of your head ends up pulling on the muscles that support your shoulder. All night long. On your back, the opposite happens: the gap is much smaller and a high pillow pushes your chin toward your chest.
| Pillow | Height | For whom | Price |
|---|---|---|---|
| AirHigh | 18 cm | For those who sleep on their side. It is the one that corresponds to almost everyone who has nighttime shoulder pain | See price |
| SojaVisco | 13 cm | For those who change positions during the night | See price |
| Calma | 12 cm | For those who sleep on their back or stomach | See price |
A simple way to check if yours is falling short: lie on your side as you sleep and ask someone to look at you from the foot of the bed. Your nose, sternum, and navel should be more or less in line. If your head falls down, you need more pillow.
Why a mattress that is too firm makes shoulder pain worse
This is where most people get it wrong, and usually with the best intentions. There is the idea that if something hurts, you should sleep on something firmer. For the shoulder, it is exactly the opposite.
A mattress has to do two things at once that seem contradictory: support the heavy areas, like the hips and lumbar region, and give way in the protruding areas, which on your side are the shoulder and the hips. If the mattress is like a board, the shoulder cannot sink in: it stays supported on the surface, bearing all the weight of the torso on the smallest possible point, and it also forces the spine to arch. If the mattress is too soft, the opposite happens: you sink in completely and your hips sink more than the rest.
What works for the shoulder is a mattress with a firm core that supports, and top layers that adapt. That is why hybrids—pocket springs on the bottom, memory foam or adaptable materials on top—are usually the best answer for those who sleep on their side: the springs provide support, and the top layers make room for the shoulder.
| Mattress | Height | Why for the shoulder | Price |
|---|---|---|---|
| Original Hybrid | 26 cm | Nine layers with pocket micro-springs. The range's balance between support and adaptation | See price |
| Altus | 28 cm | More than 2,000 micro-springs, which work more independently point by point | See price |
| VisCool | 26 cm | The same adaptation logic, with PCM temperature-regulating fabric if you get hot | See price |
| Morfeo XL | 30 cm | Reinforced springs. The one that corresponds if you weigh more than 100 kg | See price |
| Nature | 32 cm | Natural latex, which recovers its shape faster when changing positions | See price |
All Morfeo mattresses are guaranteed up to 95 kg per person. The XL is the only one with reinforced pocket springs and is the one that corresponds above 100 kg: it is not a matter of comfort, it is that a core that is not sized for that weight deforms sooner.
Which setup is right for you
Two questions
1. What position do you spend most of the night in?
2. Does any of this apply to you?
You sleep on your side, which is the profile that suffers the most from the shoulder. The Hybrid lets the shoulder sink in without the hips sinking, and the 18 cm AirHigh is the one that fills the shoulder-ear gap. The pillow is half the result.
On your side and getting hot. The VisCool has PCM temperature-regulating fabric and the same surface adaptation capacity, so the shoulder sinks in just the same without you having to spend the night uncovered. With the 18 cm AirHigh.
On your side and over 100 kg. Here the XL is not optional: it is the only one with reinforced springs, and in a mattress that sinks too much the shoulder ends up worse, not better. With the 18 cm AirHigh.
On your back is the position that puts the least strain on the shoulder, so here the important thing is not to ruin it with a pillow that is too high. The Calma, at 12 cm, keeps the neck in line without pushing the chin to the chest.
On your back and getting hot. The PCM fabric of the VisCool regulates the surface temperature, and the 12 cm Calma is the height that corresponds to that position.
On your back and over 100 kg. The XL supports the lumbar region without the hips falling, which is what makes sleeping on your back uncomfortable in a short support mattress. With the 12 cm Calma.
If you change positions all night you need a mattress that responds point by point: the more than 2,000 micro-springs of the Altus work independently, so the shoulder sinks in when you get on your side and supports again when you turn. The SojaVisco, at 13 cm, is the intermediate height.
You change positions and get hot. The VisCool adds surface adaptation to the PCM fabric, and the 13 cm SojaVisco is the height that holds up well both on your side and on your back.
You change positions and weigh more than 100 kg. The reinforced springs of the XL maintain the support in all positions, which is where the weight is most noticeable. With the 13 cm SojaVisco.
If you are coming from an old mattress, keep in mind that the body takes a few weeks to get used to a different support, and that during the first few days you can notice new discomforts in other areas. That is why Morfeo mattresses come with 100 nights of trial: the period is designed exactly for that.
When to stop trying things at home
Go get checked if any of these appear
- You cannot lift your arm, or you have clearly lost strength.
- The shoulder has been losing mobility for weeks, and it is already difficult to move even with the other hand.
- The pain goes down the arm with tingling or numbness to the hand.
- There was a blow, a fall, or a specific strain before it started.
- There is swelling, heat, redness, or fever.
- You have been waking up for more than three or four weeks because of the pain despite having changed position and pillow.
To start, your family doctor. Depending on what they find, they will refer you to orthopedics or physical therapy. Changing the mattress in the meantime can make the nights more bearable, but it does not replace that.
Frequently asked questions
Is a firm mattress better if my shoulders hurt?
No, and it is the most common mistake. The shoulder needs the mattress to give it space to sink; on a very firm surface, it stays supported on the tip, bearing all the weight of the torso on the smallest point. What you need is a firm core that supports the hip with top layers that adapt, which is exactly what a hybrid mattress does.
Does changing the pillow really make a difference?
It is the most noticeable change and the cheapest to try. If you sleep on your side and your pillow is low, your head falls toward the mattress all night and pulls on the muscles that support the shoulder. The height that corresponds to that posture is 18 cm, the height of the AirHigh, because the distance between the shoulder and the ear is greater than in any other position.
Can I sleep on the shoulder that hurts?
If the mattress allows the shoulder to sink and the pillow has the correct height, many people tolerate it without any problem. But while the shoulder is irritated, the sensible thing is to give it a few weeks of rest by sleeping on the other side or on your back. And if it hurts regardless of whether you support it or not, that points to the cause being in the joint and not in the bed.
Is it bad to sleep with your arm under the pillow?
It is one of the postures that is most advisable to correct. Keeping your arm above your head or under the pillow reduces the space through which the shoulder tendons pass, and maintaining that position for hours is what causes the pain to appear in the early morning. Hugging a pillow is the alternative that works best.
Why does the pain get worse right at night?
Several things come together: the weight of the torso comes to rest on a small joint, certain postures compress the space through which the tendons pass, and you are still and without distractions, so you notice a discomfort much more than you did during the day when you barely registered it.
How long does it take me to notice the difference with a new mattress?
The body needs a few weeks to adapt to a different support, and it is not uncommon to notice new discomforts during the first few days. That is why Morfeo mattresses come with 100 nights to try. The pillow, on the other hand, is noticed much sooner: if the height was the problem, you will know in a few days.
We manufacture in Yecla, to order
Each mattress is produced when you place the order and arrives in 12 business days, with assembly included at home and free of charge. 100 nights to try and a 10-year warranty.
