ABSTRACT
A well-qualified sleeping system has to fulfil many needs depending on personal requirements, and has to be reliable for different sleeping postures. Most authors consider a resting-place being ergonomically justified when the entire musculoskeletal system can recuperate well: muscles have to relax while the unloaded intervertebral disks are rehydrating. Unfortunately this is not the case for many chairs, couches and beds that are available on the market: despite a growing consciousness towards back problems the vertebral column is often supported insufficiently. We discuss below the mechanical properties of a sleeping system that largely determine these supporting qualities.
