Why position matters more than anything#

If you only use one factor to choose a mattress, make it your sleeping position. It decides where your body pushes into the surface and which parts need to sink or stay supported to keep your spine neutral. The same mattress that's perfect for a back sleeper can leave a side sleeper with a sore shoulder, because their bodies meet it completely differently.

The general target: medium-firm#

Across positions and body types, the research points to medium-firm as the best starting point, a systematic review of 39 studies found it best supports comfort, sleep quality and spinal alignment.1 From there, you adjust softer or firmer based on how you sleep.

Side sleepers#

The most common position, and the one that needs the most cushioning. Your shoulder and hip are the widest points and must sink in so the spine stays straight, otherwise it bends toward the mattress and you wake with shoulder or hip pain. Aim for medium to medium-soft, with a comfort layer deep enough to cradle those joints. Memory foam and hybrids with a generous top layer work well.

Back sleepers#

Back sleeping spreads weight fairly evenly, but the lower back needs support so the lumbar curve isn't left unsupported (too firm) or allowed to sag (too soft). Aim for medium to medium-firm. A hybrid or supportive foam that fills the lumbar gap without pushing the hips up is ideal.

Front (stomach) sleepers#

The trickiest position for spinal health, the hips tend to sink and over-arch the lower back, and the neck is turned all night. Aim for medium-firm to firm to keep the hips lifted and the spine flatter, and use the flattest pillow you can. Many front sleepers benefit from gradually shifting to back or side sleeping.

Combination sleepers#

If you change position through the night, prioritise a responsive surface that's easy to move on, latex or a hybrid rather than deep, slow memory foam, at a medium feel that compromises between positions. Ease of movement also protects sleep continuity, and medium firmness is linked to shorter sleep latency and more stable sleep architecture than a soft surface.2

Body weight fine-tunes it#

Within your position, weight nudges the ideal: heavier sleepers should lean firmer to avoid sinking, lighter sleepers softer so they get enough contouring. Fit is ultimately individual, comfort depends on the interaction between sleeper and surface,3 which is why a home trial matters.

Find your match in our firmness guide, or jump straight to position guides for side, back and stomach sleepers. Or take our quiz for a personalised recommendation.

References#

  1. Caggiari G, Talesa GR, Toro G, Jannelli E, Monteleone G, Puddu L. What type of mattress should be chosen to avoid back pain and improve sleep quality? Review of the literature. Journal of Orthopaedics and Traumatology. 2021;22:51. doi:10.1186/s10195-021-00616-5
  2. Hu Z, Wang Y, Li L, et al. Effects of Mattress Firmness on Sleep Quality and Sleep Architecture. Nature and Science of Sleep. 2025;17:865–878. doi:10.2147/NSS.S503222
  3. Robbins R, Quan SF, Barger LK, et al. Validation of the Boston Mattress Satisfaction Questionnaire. Frontiers in Sleep. 2025;4:1509420. doi:10.3389/frsle.2025.1509420