Prices shown are approximate. Verify current pricing on the retailer’s site before purchasing.
Editor’s note: This article reflects general mattress retail industry knowledge from the perspective of a former mattress store owner.
I owned a mattress store for eight years. I sold thousands of mattresses. I also handled hundreds of returns and exchanges, which means I got to see exactly which buying decisions tended to go wrong.
One mistake came up far more often than any other.
The biggest mistake: buying for the wrong sleep position
The single most common reason customers returned mattresses was that they had bought a mattress that did not match their actual sleep position. Specifically: side sleepers buying mattresses that were too firm, and stomach sleepers buying mattresses that were too soft.
The pattern was almost always the same. The customer came in convinced they wanted “firm support” because that is what mattress marketing has trained them to want for back health. They tested mattresses for 5-10 minutes in the showroom, picked one that felt supportive, and took it home. Three weeks later they came back complaining of shoulder pain (side sleepers) or lower back pain (stomach sleepers).
Why this keeps happening
Three reasons:
1. The “firm equals supportive” myth
Mattress marketing has spent decades equating firmness with support. The reality is more nuanced: a side sleeper on a firm mattress will have unsupported gaps at the waist while shoulder and hip dig in painfully. The right mattress for a side sleeper is firm enough to support the spine but soft enough to let the shoulder and hip sink in for proper alignment.
2. The 5-minute showroom test
Five minutes lying on a mattress in a store is not enough to know how it will feel after 8 hours of sleep. Many comfort issues only emerge after the first 30-90 minutes. Showroom testing biases buyers toward the firmness they think they want, not the firmness their body actually needs.
3. Pillow assumptions
Customers test mattresses with showroom pillows, then sleep at home with their own pillows. The combination matters. The right mattress with the wrong pillow can cause neck pain that gets blamed on the mattress.
The right firmness by sleep position
The general guidance, from years of seeing what came back and what stayed sold:
Side sleepers
Recommended firmness: Medium to medium-soft (4-6 out of 10).
The mattress needs to allow the shoulder and hip to sink in just enough to keep the spine straight. Too firm and you get shoulder pain (it cannot sink in, so it presses up against the bone) or hip pain (same reason).
Best picks: Nectar Premier (medium with deep contouring), T&N Original (medium with adaptive feel), Saatva Classic Plush Soft (premium plush option).
Check Current Nectar Premier Price on Amazon →
Back sleepers
Recommended firmness: Medium-firm (5.5-7 out of 10).
The mattress needs to support the lumbar curve without creating pressure points. Too soft and the hips sink too far, causing lumbar strain. Too firm and the lower back is unsupported because the mattress does not match the spine’s natural curve.
Best picks: T&N Original (medium-firm), Saatva Classic Luxury Firm (firm enough for support, soft enough for comfort), Nectar standard (medium-firm).
Check Current T&N Price on Amazon →
Stomach sleepers
Recommended firmness: Firm (7-8.5 out of 10).
Stomach sleepers need firm support to keep the spine from arching. The hips should not sink at all. Soft mattresses cause lumbar strain that compounds over time.
Best picks: Saatva Classic Firm, Linenspa 10″ Hybrid (firmer hybrid feel), or any innerspring with minimal pillow top.
Check Current Saatva Pricing →
Combination sleepers (no dominant position)
Recommended firmness: Medium-firm (6-7 out of 10).
If you change positions throughout the night, you need a mattress that handles all positions reasonably well. Pure plush mattresses fail stomach sleepers; pure firm mattresses fail side sleepers. Medium-firm is the safe middle.
Best picks: T&N Original or Saatva Classic Luxury Firm.
The other common mistakes
Behind “wrong firmness for sleep position,” the other top mistakes I saw:
2. Buying based on the showroom feel without using the trial period
Customers came back saying “I knew within a week it was wrong, but I figured I should keep trying.” The trial period exists exactly for this. If a mattress is wrong, return it. Online brands make this easy — one email, free pickup, full refund.
3. Skipping the foundation upgrade
The new mattress on the old box spring sleeps almost the same as the old mattress. Most warranties require a solid foundation. The math: spending $1,000 on a mattress and $50 on a 15-year-old box spring wastes most of the mattress upgrade.
4. Buying too much mattress for the budget
Stretching budget to a $2,500 mattress when $800 would have served you well. Mattress quality scales with price up to about $1,500. Above that, you are paying for materials and longevity rather than basic comfort. If your needs are average, a $700 mattress is enough.
5. Buying too little mattress for the need
The opposite mistake: a side sleeper with shoulder pain buying a $250 budget mattress that does not have enough comfort layer. The wrong tool for the job. If you have specific orthopedic concerns, the budget tier is usually too thin.
6. Forgetting about temperature
Hot sleepers buying memory foam without cooling features. Memory foam contours well but retains body heat. If you run hot at night, you need either a hybrid (coil airflow), Purple grid (open structure), or memory foam with phase-change cooling cover (Nectar Premier).
7. Buying without checking the warranty fine print
“Lifetime warranty” sounds great until you read that body impressions under 1.5 inches are not covered — which means the actual reasons people replace mattresses are excluded. Read the warranty before buying.
The fix
If I were giving one piece of advice to someone shopping for a mattress today, it would be: match the firmness to your actual sleep position, not to what mattress marketing tells you to want.
Side sleeper? Medium to medium-soft. Back sleeper? Medium-firm. Stomach sleeper? Firm. Combination? Medium-firm.
Get that right and you avoid 80% of the comfort issues I saw return to my store. Get it wrong and even the best mattress will feel uncomfortable.
Reminder: Mattress prices change constantly. Confirm current pricing before purchase.




