Glossary
Body impression
The permanent dip a mattress develops where you sleep — the most common durability failure. Warranties only treat it as a defect past a stated depth threshold (commonly 0.75–1.5 inches, measured with no one on the bed). Many real-world sags that ruin sleep never reach the threshold, which is why the threshold number matters more than the warranty's advertised length.
Related: prorated warranty · foam density