Mattress design – the history The human body is a wonderful machine with a very powerful computer. To work efficiently though, it needs sleep and it needs rest. Although science has not yet uncovered one definitive reason or restorative mechanism, the consequences of sleep deprivation indicate that sleep is vital for life. When we don’t get enough sleep, our mood becomes irritable, our memory is reduced and our judgement is compromised. Equally, when we don’t get enough rest, our muscles, joints and nerves and especially our spine lose strength and movement. We develop aches and pains, feel tired etc. In the longer term, we greatly increase our risk of poor health from obesity, diabetes and cardiovascular disease. The question then becomes, ‘how can we best optimise our sleep and body rest?’ Traditionally, humans have looked to ‘comfort’ as the answer. 1. Comfort cushions Because it is very curved,the human body is not comfortable sleeping on flat, hard surfaces. Not only does it make it more difficult to fall asleep and stay asleep, but the body is forced to become flat and out of alignment. Muscles, joints and nerves are stressed and high-pressure spots form which restrict blood-flowwhich in turn can cause back, shoulder and hip pain as well as bed sores and skin ulcers.To compensate for this, for thousands of years people have used animal skins, made mattresses out of leaves, straw or grass, made cushions filled with wool or cotton, and have even filled sewn animal skins with water, all in an effort to produce a soft and comfortable sleep surface. In the 20th Century, with the advent of machinery to manufacture springs at affordable prices, the inner-spring mattress offered a comfort cushion that was durable, hygienic and reasonably comfortable – at an affordable price for consumers. (a) The hour-glass springwas the first spring type used in beds, with about 150 springs in a Double bed mattress.This increased to 180, then 210 and eventually 312 for a Queen size mattress. (b) The pocket-spring, the constant-diameter spring (LFK) and the woven-wire followed in the 1950s and 1960s. (c) Latex cores, water-bed bladders, air bladders and poly-urethane foam cores were softer innovations that followed in an attempt to replace the hard and lumpy feeling of metal springs. (d) In the 1970s, bedding manufacturers incorporated extrasoftness through more padding with the advent of the Pillow-top look and later the Euro-top tailored look. (e) The Health Professional Endorsed ranges sprouted in the 1970s and 1980s. Bearing model names ending in ‘-pedic’and similar, such mattress models were cleverly marketed as being greatly enhanced in terms of ‘moresupport’ and increased
healthbenefits. The term ‘comfort’ began to be used synonymously with ‘support’; however, little evidence was provided to substantiate these claims.After some 40 years, consumers worldwide have become sceptical of the marketing tricks and innuendo of the multinational bedding companies generally and so only a handful of these ‘endorsed’ products are labelled as such today. (f)The American market has led the world in claims of using thick and soft padding layers as a means of improving support. Whilst these have improved sensations of comfort and do lessen the blood-flow restrictions caused by the metal springs and helical wires below, the concomitant claims of ‘spinal-arch support and body alignment’ have been grossly overstated.The human body varies significantly in weight and shape along its length. When these thick foam layers of 50 mm or more are used on top of the mattress, the varying weight and shape of the human body is borne by the thick foam padding, leaving a layer of springs beneath that barely contour at all. Essentially, then, these mattress units constitute of little more than a thickly padded mattress resting on a wire-spring base. Further, because the thick foam padding alone constitutes the mattress component, these layers are responsible for an unfortunate and unpopular side effect: deep, uncomfortable body-impressions. Initially, these body-impressions were tolerated by consumers who could turn their mattress over, utilising both sides of the mattress to extend the life of the product before the need to purchase a replacement. However, the bedding industry has woken up to this, introducing and promoting 1-sided mattresses as a means of ensuring short-term obsolescence. The sale of 1-sided mattresses has proliferated in recent years, again with no evidence to substantiate their use. The only benefit of this construction is that – using less materials, the mattress is lighter and easier to turn and also cheaper to manufacture. (g) As the use of thick padding layers became the norm in the bedding industry, some manufacturers recognised and acknowledged the discrepancy between ‘comfort’ and ‘support’ provided by mattresses and that the products hitherto produced by the industry fell well short of its claims of providing both. To address this, they introduced products marketed as being scientifically advanced, such as memory foam (‘developed by scientists at NASA’) and gel-infused comfort layers. In reality, although these innovations did improve comfort and sought to address the varying weight and shape profile of the human body, they were little better than the thick foam padding that they sought to replace as they functioned in the same way. The slick marketing that accompanied these products cleverly incorporated scientifically generated pressure maps that formed a smokescreen, but again these did little more than conflate pressure reduction(that is,‘comfort’) with ‘support’. As the bedding industry seems to rely on perpetuating the myth that posits comfort as being synonymous with support, marketing departments have done much to promote claims of scientific rigour without providing much evidence to substantiate those claims. Sceptics of the industry could be forgiven for thinking that this promotion of extra mattress padding has done little more than provide a rationale for padding the profits of
the industry. At present, no scientific study has reported on the benefits of one product over another in terms of greater health benefits from increased support or anatomical alignment, despite the claims of the industry’s leading brands. Any testing that has occurredhas tended to be in-house, away from the rigour of peer-reviewed literature. Despite this, the marketing departments of the large manufacturers continue to pronounce their claims as fact. 2. A mattress designed as a support structure In late 1996, Mario Piraino, a Structural Engineer turned Furniture and Bedding Retailer, put on his Engineering hat and turned his attention to the question of whether the prevailing taken-for-granted mattress designs promoted by the industry were really best for helping people to optimise their sleep.Because injuries had been documented from activities that cause incorrect natural body alignment, he set about designing a mattress to support the human body in its natural alignment, with specific emphasis on the shoulders, spine and hips. Although the support function of mattresses was well recognised and promoted by the industry, Mario was surprised to find that there was little scientific data to suggest just what that support should entail. Therefore, as a starting point, he began to apply Engineering principles to the design of his mattresses, taking into account the structural properties of mattress construction materials and the varying distribution of weight and shape along the length of the human body. He had hardly started using basic support structure theories when he realised that this would lead him far, far away from what the industry regarded as ‘the norm’. Designing the mattress as a support structure requires knowing how the body varies in both shape and weight along its length; however, there was no published data providing this information. With the help of the Chiropractors’ and Physiotherapists’ Associations as well as the Melbourne City Morgue, Mario settled on a model body and a set of common incremental variations on which to base his calculations. These are tabled in Appendix A. The results of these preliminary calculations had significant implications: (a) Weight. A transverse slice of the body at the lumbar (or tummy) area was some 2 times (or more) heavier than an equivalent slice at the chest and upper shoulder area.Simple calculations yielded the answer that mattress springs under the lumbar needed to be at least double the firmness ofthose in the shoulder areato prevent the occurrence of a‘hammock’ effect. (b) Shape.Measuring shoulder width : waist width : hip width and the depth of lumbar curves, it was evident that the springs under the lumbar (or tummy) needed to be at least 4 times firmer than those in the shoulder and hip areas or the spinal arch would flatten with the body on its back, and a hinge would form at the L2–L4 area plus the bottom shoulder would twist and rotate when the body was on its side.
These simple calculations pointed to mattresses requiring critical zones in the shoulder and lumbar areas that were in the order of 800% different in firmness.For comparison, mattresses on the market at that time had either no zones or, those that did, had 3, 5 or 7 zones (each of equal width and not placed at the appropriate positions to the relevant body parts they were supposed to support) that differed in firmness by a mere 10%. Trading as ‘His & Hers Orthopaedic Beds’ and later as ‘Beds for Backs’, Mario designed and produced twomattress ranges and onebase range that incorporate body zones reflective of actual weight and shape variations in the human body. He also designed an electric bed mechanism with lumbar support. (a) The Ergo~linemattress range, which features inter-related zones of pocket springs of fixed firmness each placed in specific positions that suit most body types. (b) The Ergo~shapemattress range, which features a soft shoulder zone and a variable lumbar zone that the sleeper can adjust both in position and magnitude. Of course, the lumbar zone on each side of the mattress can be adjusted independently by each partner. (c) The Ultra-fit Base range, which incorporates European-type cross-slats that can be given a positive or negative displacement to align the body as needed whilst at the same time allowing (i.e. adjusting) for the varying compression of the mattress arising from variations of weight that occur along the length of the body. (d) The Ergo~multi range of electric adjustable beds, which incorporate a lumbar support that protrudes automatically as the chest area is raised and then disappears when the chest is lowered.
4. Research, comparisons and Bedding Symposium (a) Associate Professor Nicholas Haritos School of Engineering, Melbourne University investigated and concluded that ‘Tables of Relative Firmness calculated by Mario Piraino for Shoulder, Lumbar and Hip areas for various levels of embedment in springs as well as different shoulder/waist/hip widths were correct. See Appendix A. (b) Dr Ray Hayek of Macquarie University Department of Chiropractic, tested the effectiveness of the Ergo~shape mattress using Low level X-rays. . Dr Hayek observed ‘disc-wedging’ and higher pressure areas occurred with flat mattresses of uniform firmness. Both the high pressure areas and the disk wedging decreased on the Ergo~shape mattress. – See Appendix B.
(c) Dr Noel Lythgo of Melbourne University Department of Physiotherapy measured levels the spinal distortion occurring on both a ‘male’ and a ‘female’ body when sleeping on 15
different mattresses â€“ included the better-known brands as well as those endorsed by Health Bodies. Dr.Lythgo found that (i) very high pressure areas were formed at hips and shoulders with bodies on their side and (ii) the distortion at the waist from normal mattresses was constant at 7.2 degrees whilst pressures were much lowered and distortion reduced to only 1.5 degrees when bodyalignment was corrected/adjusted using the Ergo~Ultra-fit Base in conjunction with a common latex mattress and a Memory Foam Tempur mattress. See Appendix C. (d) A Bed Symposium was held at the University of Melbourne in October 2006 under the auspices of: Melbourne University, Macquarie University and Australian Spinal Research Foundation. The event featured a presentation by the keynote speaker Professor Alan Hedge from Cornell University in New York State, U.S.A. and a presentation by Ingeborg Duurkoop, MSc., Product Design ManagerVita Comfort Foams who travelled from Holland for the event. A discussion panel was convened at the conclusion of additional presentations by medical, health and bio-mechanical experts. The panel vigorously discussed key aspects of the presentations and fielded questions and comments from the audience ultimately arriving at 12 key conclusions including: - All Panel Members and attendees who were currently, or had in the past, acted in the capacity of health professional confirmed there were no modules within their study dedicated to bed design and effectiveness and unanimously agreed training modules should be developed and applied in the various education programs. - There was unanimous agreement that product branding and labelling by manufacturers were predominantly misleading and there was a requirement for claims to be substantiated. - Strong opinion was shared by all Panel Members and attendees that the consumer and special needs market could benefit from the introduction of industry standards relating to product performance and beneficial outcomes. The recommendations of the panel of professional advisers focussed on the potential benefits associated with the establishment of an independent international research body to facilitate industry research and appropriate communication of bedding features as they should be presented to the consumer market and health professionals. Mario Piraino has also written an extract on a) the Pressures Produced/Reduced by Mattresses and Toppers on the human body laying on a bed. See Appendix D. b) Application of Scientific Principles in supporting the Human Body on a bed mattress. See Appendix E.