Before you buy a new mattress or topper, sit on its edge the way your mother will sit on it every night. The edge decides the first move of each trip: sitting up, turning her legs, and standing. A mattress that looks right in the room can make that move harder.

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Decide what you are comparing

Write down the three options on the table: keep the current mattress, add a topper, or replace the mattress. Each one changes the height of the bed and the feel of the edge, so compare them on the same bed frame, not against each other in the abstract.

Sit-test the edge

Have your mother sit on the edge of each mattress with her feet flat on the floor. Note whether her knees end up level with or below her hips, and whether she can sit without sinking. Then, if she is safe to do it with you present, have her stand without using the bed frame for leverage. Watch whether the edge lets her feet stay put or pushes her backward. Ask her physical therapist or physician whether a particular height suits her transfers, since that is a clinical question and not one this desk can settle.

Check the edge firmness

Press down on the edge and then on the center. A soft edge gives way under her weight and makes the first push to stand take longer. A firm edge gives her a solid place to push from. Compare the two spots on each mattress and write down which edge felt steadier.

Measure the height change

Measure the top of the current mattress and the top of each candidate on the same frame, then compare the new height against the bedside table and the spot where her feet land. A thicker mattress raises the bed and changes the height she has to reach. If you already set the bed height for her, a new mattress means you set it again.

Ask before you pay

Ask the seller in writing whether the mattress can be tried at home, what the terms are if it does not suit, and who handles removal of the old one. Keep the answer in the sales paper, not in your memory.

Write down

Write the model you chose, the edge firmness impression, the bed height before and after, who was present for the sit test, and the answers to the questions you asked. If the mattress changes the night route, add a line to the route notes so the next person knows the bed is higher.

The desk's rules for handling clinical questions are on How we write this desk.