For those not experiencing troublesome back pain, a firm mattress is will generally be more comfortable. ... Firm mattresses are generally better for those who sleep on their back, because they provide a more stable and even surface. Stomach sleepers tend to fare better on a firmer mattress, too.
They're also recommended for lighter individuals as a harder mattress can end up not compressing for them at all. Softer mattresses are generally better for those who sleep on their side, as they better cushion the shoulders and hips.
Sleeping on a mattress that is too firm can cause aches and pains on pressure points. A medium-firm mattress may be more comfortable because it allows the shoulder and hips to sink in slightly. Patients who want a firmer mattress for back support can get one with thicker padding for greater comfort.
