It has come time to replace our IKEA mattress. It was a cheap memory-foam mattress and, at the time that we bought it in 2015, a friend of ours warned that it would probably only be usable for three or four years and I did not believe her. As it stands, it is a bit more than six years old, now, and it is a nightmare. Still, I think it cost a bit over 350€, at the time, and a new mattress from a shop that *assures* me that theirs will last a decade stands at about 800€, which, in terms of price-per-year, is not worlds apart.
But I really baulk at the thought that a mattress can't last longer. Our IKEA one could have been replaced two years ago, with a clear conscience, given that it was already beginning to become seriously uncomfortable and misshapen. (And my weight has been more or less stable at just under 70kg for the last six years so that is not the root of the issue.)
Memory foam is clearly just a catastrophically bad material from which to make a mattress, barring special ones for people with disabilities or injuries that need its special properties. What I now know is that it just changes shape during the night and that that has two consequences: firstly, it makes it uncomfortable to change sleeping position and healthy, normal humans actually do do that, during a night, naturally. More significantly, it changes shape in a way that sinks in the middle -- I find that I tend to fall asleep on my back and then roll over and, because the mattress has subsided, this leads to a painfully contorted spine.
As the memory-foam ages, it seems to become more and more prone to this change of shape as its temperature changes, during the night, from my experience.
But what *IS* the best material or mattress technology, from the perspective of sustainability?
The fancy-pants, specialist mattress shop that I visited, during the week, says that "Kaltschaum" (cold foam??) is the best because it does not, supposedly, change its properties as the temperature of the foam changes but I struggle to believe that -- foam, surely, must age badly and fancy cut-out patterns and cross-sections-in-display-cases cannot change that.
Are old-fashioned, metal springs simply out of fashion or is there a reason why foam -- any foam -- is in vogue? (With modern manufacturing capabilities and modern materials, I struggle to believe that it is impossible to encase springs in a way that is not *both* ergonomic and robust for much, much more than six-to-ten years!)
Something else?
Moreover, does longevity equate to sustainability in the cases of a mattress? It seems self-obvious but, perhaps, it actually is better to replace one's foam mattress every six-to-ten years than to build (and transport) one made out of a potentially heavier and more costly material -- I wouldn't really know.