Guide · Updated 2026
Choosing a mattress when your back hurts
The most common question we get on the floor, and the one most often answered badly. Here's what we tell people, including when the answer is that a mattress isn't your problem.
We sell mattresses, not medical advice. Persistent or severe back pain is a conversation for your doctor or physiotherapist. What follows is what we've learned about beds.
Medium-firm, not firm
The instinct when your back hurts is to buy the hardest bed in the shop. It's usually the wrong move. A mattress that's too firm leaves an unsupported gap under the lumbar curve and concentrates pressure at the shoulder and hip; a mattress that's too soft lets the hips drop below the shoulders and the spine bends all night. The target is neutral alignment, and for most people with lower-back pain that lands around firmness 5 to 7.
Position changes the answer
- Back sleepers — firmness 5–7. Enough give for the lumbar curve to be filled, enough support that the hips stay level.
- Side sleepers — firmness 4–6. Shoulder and hip need to sink or the spine bows sideways.
- Stomach sleepers — firmness 7–8, and the hardest position to sleep pain-free in, because the lower back arches. If you can retrain to your side, that usually helps more than any bed will.
Zoned support and why it matters
Some hybrids use firmer coils through the middle third of the mattress, under the hips, and softer coils at the shoulders. That's a real feature, not marketing — the hips are the heaviest part of the body and the first place a mattress gives out.
Check the support under the mattress
A perfect mattress on slats spaced more than 3 inches apart, or on a queen frame with no centre leg, will sag in the middle within a year and take your back with it. This is also the single most common reason a warranty claim gets refused. Check the frame before you blame the bed.
When it isn't the mattress
If you also wake stiff after a night in a hotel, or the pain is there through the day, the bed probably isn't the cause. And if your current mattress is under three years old and still flat, replacing it is unlikely to be the fix. We'll tell you that on the floor rather than sell you something that won't help.
What we'd show you
Beds we point back-pain customers at
Back pain FAQ
Common questions
Is a firm mattress better for back pain?
Not automatically — that's the most common misconception in the category. Research generally points to medium-firm rather than firm. A mattress that's too hard leaves a gap under the lumbar curve and creates pressure at the shoulder and hip.
How long before a new mattress helps?
Give it two to four weeks. Your body adapts to whatever it has been sleeping on, and the first week on a properly supportive bed can feel worse before it feels better.
Can an adjustable base help back pain?
Many people find it does. Raising the head and knees slightly — the zero-gravity position — takes load off the lumbar spine. It's worth trying one in the showroom before you decide.
Should I put a board under my mattress?
It's an old trick that mostly signals your bed is finished. It makes a sagging mattress feel firmer without fixing the support problem underneath.