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Mattresses Matter: Ergonomic Guidelines

How to Sleep Soundly

Written by Alan Hedge, PhD, CPE; Reviewed by Richard D. Guyer, MD

In Hans Christian Andersen's fairytale The Princess and the Pea, a princess is unable to get a good night's sleep because a pea has been placed under her mattress—which is actually 20 mattresses piled high! One moral to this tale is that the quality of what you sleep on matters to the quality of your sleep. In fact, when we are asleep, our body is compressed by gravity in a different way than when we stand upright, and we need to be fully supported by the mattress and its supporting structures. For this reason, the mattress has been called an "anti-gravity machine" that makes it possible to maintain the natural shape of the spine when sleeping.[1]
Although we spend around one-third of our life lying on mattresses, and although it is estimated that about half of all Americans experience at least occasional sleep difficulties, there has been relatively little scientific study of mattress design.[2] Poor mattress design can create inappropriate body support, and this in turn may cause muscle discomfort and back pain.[3] So what are the features of a good mattress? Does it matter if it's too hard or too soft? Does it matter if it's an orthopaedic mattress? Is a mattress even important?
Recent Mattress Study
In a recent study of mattress ergonomics that tested 12 women, lying on an incompressible wooden surface was compared with various mattresses. All of the mattresses were judged as significantly more comfortable than the wooden surface, but there were no significant differences between mattress types, even though these included orthopaedic and normal designs. Measures of shoulder, elbow, hip, knee and ankle body contact pressures showed few significant differences, and surprisingly, there were no significant associations between measures and the comfort ratings.[4]

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However, how hard or soft a mattress feels is thought to be an important factor in reducing or preventing back pain.[5] Comparison of sleeping on a futon or a softer air mattress showed that sleep onset latency, waking after sleep onset, and the sleep efficiency index were comparable for both mattresses, but subjective sleep evaluation tended to be better for the air mattress.[6] A study of sleep quality and bed firmness showed that 4 of 9 male subjects slept significantly better on the softer mattresses, while 2 slept better on the harder mattress. The greatest difference in sleep quality occurred when changing from the subject's own mattress to one of the test mattresses, and the authors concluded that it may take several days to adapt to a new sleep surface.[7] This may be why business travelers often report sleep difficulties.[8]