Independent hybrid & innerspring mattress research
Mattress Research

Why Mattresses Sag

Common reasons mattresses develop body impressions or sagging and what construction and support can influence.

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Materials compress over time

Foams and fibers can soften and compress with repeated loading. Coil fatigue, foundation problems and improper support can also contribute.

Sagging versus normal impressions

Warranty definitions vary. A visible impression may need to reach a specified depth before it qualifies as a covered defect.

Reduce avoidable stress

Use a compatible foundation, rotate when the manufacturer allows it and follow care instructions.

Use this when comparing real mattresses

Take the construction principle above and compare it against the manufacturer's current specifications, trial terms and warranty rather than relying on marketing labels alone.