If, like me, you've recently purchased a mattress, you'll know it's an astoundingly tedious and soul-depleting process – rendered only slightly less awful by the fact that when you do finally collapse, exhausted by indecision, in the middle of the beds department, there are plenty of places to lie down. Long ago, maybe mattress-shopping was a simple choice between "firm" and "soft", but these days it's a thicket of dilemmas. Memory foam, wool, gel, fibre? Solid-slatted or sprung-slatted? Lumbar zoning? Perhaps a pillow-top? This complexity at first seems hard to explain. Sure, it's nice to have options, but why deliberately aggravate customers, delaying the moment of purchase with so many extra decisions? Aren't mattress-makers aware of one of the best-known truths of consumer psychology: that too much choice makes people miserable?