Required stiffness distribution in a mattress for an optimal curvature of the human spine during bedrest

Many cases of low back pain are due to or aggravated by bad bedrest, frequently caused by an incorrect body support. The optimal sleeping system has a high conformity, i.e. it supports the human body such that the spinal column adopts its natural position, which is assumed to be the same as it takes in the upright position. An objective and scientifically sound method is needed to determine the right sleeping system for each individual. A two-dimensional finite element analysis on individuals resting on mattresses made it possible to predict the curvature of the spinal column (a) in posterior and (b) in lateral recumbency. Measurements are made and compared to the predicted results to adjust and to refine the model. With the resulting model one can examine for each individual both which stiffness distribution in the mattress gives an optimal body support and which existing sleeping system gives the best approximation of an optimal support.