Side sleeping puts weight on the shoulder and hip, so the mattress needs to let them sink in while keeping the spine level. Which? says side sleepers need their shoulders and hips to sink sufficiently into the mattress, without the neck and waist sinking too far Which?. A regular side sleeper needs a mattress soft enough for the hips and shoulders to sink in just enough, without the spine losing a neutral position Which?.
Why side sleeping changes what you need
When you lie on your side, your shoulders and hips press into the mattress while your waist and neck need support. CHOICE says a soft mattress will support the body's curves for side sleepers CHOICE. Which? warns that a mattress that is too soft lets you sink in too much, which can cause misalignment Which?. A good side-sleeper mattress should not be overly firm, because a too-firm mattress may not support the shoulders or hips and can curve the spine Which?. CHOICE tests this by marking five points on a test dummy's spine to check alignment when lying on the side, and checks that no parts sink too far into the mattress CHOICE.
Firmness depends on your weight
If you are petite or lighter than average, look for a mattress that lets your body sink in while supporting your spine's curvature Which?. If you are heavier than average, as a general rule you need a denser or firmer mattress, with a higher density of foam or springs Which?. Consumer Reports assesses how suitable each mattress is for side sleepers of petite, average and large sizes Consumer Reports.
Mattress types that test well for side sleepers
Which? says hybrid and pocket sprung mattresses fare much better for side sleepers in its tests, though some foam and open coil models also score well Which?. CHOICE says its tests found no evidence that foam or spring mattresses suit particular sleeping positions, and that neither type is objectively better CHOICE.
Brand firmness labels aren't comparable
Many define mattress firmness and softness however they want to, outside of the official standard for mattresses, or using their own criteria or firmness scale. You can't rely on these to compare firmness between brands Which?.
How to test before you buy
Lie on your side in the shop or during a home trial period. Check that your shoulders and hips sink in while your spine stays level. Which? says it is tricky for mattresses to achieve optimum side-sleeping support in its tests, and a good side-sleeper score usually means a good all-rounder Which?.
Durability consideration for side sleepers
The Sleep Foundation, a review site that earns from shop links, says heavier sleepers may find that their mattresses begin to sag prematurely, while side-sleepers may find excessive sagging around the hips and shoulders Sleep Foundation.
Get a personal answer with Bed Fit
Bed Fit on the bed.chat home page asks nine quick questions about your weight, sleep position, budget and country, then tells you the mattress type, firmness range, size and what to check before you pay.