While individual preference is probably the most important factor in determining the best mattress for each person, there are some general rules of thumb in what constitutes a good mattress.
In general, most people prefer a firmer mattress that gives the spine more support. While there is no definitive literature that absolutely supports this claim, it makes sense that it is beneficial to have support for the spine while sleeping.
It is thought that a mattress should provide support for the spine at all points (along the spine’s natural curves), and keep the spine in the same body position as good standing posture.
While a firm mattress is usually good, if the mattress is too hard it can cause aches and pains in pressure points, such as the hips. Patients who have inflammation of the bursa over their hips (greater trochanteric bursitis) can be especially susceptible to aches from a mattress that is too firm.
People who sleep on their sides – with pressure points at their hips and shoulders pressed against the mattress – may also feel more sensitive to a firmer mattress.