Too hard, too soft, or "just right"
Too hard
A mattress that is too hard does not sufficiently adjust to your body. This can lead to blood circulation dysfunctions, pressure points, and numb arms.
Too soft
If your mattress is too soft, you require too much strength to carry out sleeping motor functions, i.e. the necessary energy needed for changing positions during sleep. Both impede restorative sleep.
Just right
Sleeping correctly means that the spine should have the same form when reclining as when standing, e.g. perfectly straight when in the side position. The slatted frame and mattress must bear the body's weight so that your spinal disks, which are burdened during the day, can regenerate.
A good bed system allows you to individually adjust the balance between "too hard" and "too soft", depending on body size, weight, and shape.
