Back sleepers, congratulations: you drew the good card. Sleeping on your back spreads your weight across the widest possible area, which makes yours the easiest position to support — the one every mattress engineer secretly designs for. So why are you here reading this, presumably with a stiff lower back? Because "easiest to support" comes with an asterisk the size of a king mattress: back sleeping is also the easiest position to get QUIETLY wrong, and the place it goes wrong is your lumbar spine.
My family's mattress disaster is the case study I can't stop telling: my parents bought a showroom-recommended bed, and within months the foam under my 6'4" dad's hips — the heaviest part of any sleeper — had given up. His hips sank below his shoulders, his lower back arched to compensate, and he started waking up in pain on a mattress that had felt perfectly supportive in the store. Everything a back sleeper needs to know is hiding in that story.
The whole game: hips level, lumbar filled
Lie on your back and your body asks the mattress for two things at once. First, hold the hips UP — they're your heaviest zone, and if they sink below shoulder level, your spine tilts downhill into your mattress and the lower back arches all night. Second, fill the small gap under your lumbar curve — your lower back isn't flat, and a surface that ignores the curve leaves those muscles holding it up themselves until morning.
Too soft fails the first job. Too hard fails the second. The sweet spot is a supportive surface with a modest layer of give on top: for most average-weight back sleepers that's medium-firm, roughly 5–7 out of 10 — with the eternal caveat that those numbers aren't standardized and shift with your body weight (the firmness scale is lies, remember). Heavier back sleepers should err firmer so the hips stay up; lighter ones can go a touch softer and still hold alignment. The free quiz turns your height, weight, and position into your actual SquishZone instead of a hand-wave.
Why hybrids fit back sleepers so naturally
Support with a hint of cushioning is practically the definition of a hybrid: a pocketed-coil core does the holding-you-up, and a thin-to-medium foam layer handles the lumbar-filling. Coils also breathe better than foam slabs and, for couples, isolate motion well when they're individually wrapped. Zoned builds — firmer coils or foam under the hips, gentler under the shoulders — are one of the few marketing features I'll actually endorse, because they attack the exact hips-sink problem back sleepers have. A firmer all-foam bed works too if you want deeper motion isolation and a quieter feel; just mind the next section extra carefully.
The durability trap is aimed at YOUR position
Here's what generic back sleeper guides skip. The classic mattress failure — low-density foam taking a permanent body impression — happens fastest under the heaviest contact zone, and for a back sleeper that's a nice concentrated dip right under your hips. Which means foam degradation converts a good back sleeping bed into a hip hammock precisely where you can least afford it. My dad's bed didn't feel wrong on day one; it BECAME wrong, one night of compression at a time.
So check the build before you buy: comfort and transition foams of at least 1.8 lb/ft³ for polyfoam and 3.0 for memory foam at average weights, higher if you're bigger (tables in the foam density chart), over a coil core sturdy enough for your weight (coil gauge guide). Every mattress in our catalog shows this layer by layer in the build construction breakdowns, and the quiz folds the durability math into each bed's SquishScore for your body automatically.