Definition of Sag

Meaning of the Term as it Pertains to Mattresses

What is Sag?

When a mattress has a lasting impression or indentation that measures deeper than an inch and a half, sagging usually occurs in the middle of the mattress, typically around where the lower back rests. Innerspring mattresses tend to experience sagging more frequently than foam mattresses. Lower-quality innerspring mattresses, generally the types that use Bonnell coils, tend to sag the most of all innerspring mattress types. Improper foundation or mismatching box-springs often increase sagging.

According to owner reviews, sagging is the largest complaint individuals have with their mattresses. Sagging usually puts a person in an unnatural sleeping position, which often results in back pain and an overall lack of necessary daily rest. The greater the depth of sagging, the higher chance an individual will experience pain or discomfort.