The way that you sleep should be used in conjunction with your BMI to find the correct firmness. Keep in mind too that most everyone changes positions all during the night. You may go to sleep on your side and wake up on your stomach, or start on your back and wake up on your side, or…truth is: we mainly only feel the experience of our mattress for the five minutes before we fall asleep and the five minutes while we’re waking up.
Soft: Best for side sleepers.
Medium: Ideal for side sleepers and back sleepers.
Firm: Good for side sleepers, back sleepers or stomach sleepers.