Side Sleepers Need Something Soft, But Not Too Soft
Sleeping on your side means that the curves of your body need to be contoured. Also where you hip and shoulder spear into the mattress it needs to be forgiving enough to alleviate pressure in those areas.
Having a mattress that is soft on top, yet still supportive underneath will be ideal for side sleepers. With a softer mattress your hip and shoulder will have better pressure relief and areas like your waist will be contoured and supported at the same time. You will still want to choose a mattress that has a good foam core or a good quality coil unit to still provide good deep support under the contouring layers. However, the necessary sink is best achieved through the added softer layers on top of it.
For side sleepers we recommend looking at a range between a 2 and 6.5 on a softness to firmness scale depending on a person weight. A heavy person may want to go towards the 6 and a lighter person toward the 2 since they will not have as much weight to sink into the mattress as a heavier person would. These mattresses range from very soft to medium and for a heavier sleeper perhaps a medium-firm.