visual Howto: Mattress indention as a measure for Spinal Support

Howto: Mattress indention as a measure for Spinal Support

It is widely recognized that the spine shape in lying position should be similar to the spine shape in upright position to have a good body support while sleeping. However, it is not always easy to quantify the spine shape while lying on a mattress. This howto document describes how mattress indention measurements can be used together with information on the body shape as a tool to evaluate the spinal support on one or more sleep systems.

1. Determine the body shape

It is necessary to determine the body shape as a reference for the evaluation process. The minimal set of information contains the widths at the shoulders, the waist and the hip region. Together with the corresponding heights this gives a rough impression of the overall body profile. For back posture evaluation, the depth and height of the back cavity is also necessary.

A more detailed information on the body shape will allow a more accurate evaluation of the body support. Ideally, the body shape is available as a set of body contours (as obtained by a Ikélo or Tatchi body scanner).

2. Measure the mattress indentation

The idoshape sensormat allows for a quick and accurate assessment of the mattress indentation with your test subject in different postures.

After capturing the mattress indentations in different postures, the idoshape software allows to extract cross sections by indicating straight lines or a more complicated sections based on line sections.

3. Analyze the body support

The overall tilt angle of the body can be calculated by aligning the body shape contour and the cross section of the mattress indentation. A positive tilt angle (head lower than hips) does not feel comfortable, so it is important to keep this tilt angle negative. On the other hand the tilt angle will need to be compensated by a hip rotation as the lower legs will not sink very deep in the mattress. Therefore we prefer a negative, but small tilt angle.

By introducing a kink angle between the upper part of the torso and the lower part, the deformation of the body contour can be further matched to the actual mattress indentation. If the body contour is unavailable, the matching can also be simulated by a simplified representation of the body:

A kink angle in side posture is a measure of the (mis)alignment of the spine. A bigger kink will result in discomfort or even pain in the lower back.


This methodology provides a set of parameters that can be used to score individual sleep systems or to compare a set of mattresses. It could also be used to evaluate the influence of (the height of) a pillow or the addition of a topper.

Most often a particular mattress or sleep system will be better suited for a specific body type. In some cases, the sleep system itself can be adjusted to optimize the body support.

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