M&S Stay Cool Pure Cotton Mattress Topper im Test

The M&S Stay Cool Pure Cotton Mattress Topper puts a polyester fibre fill inside a 200 thread count cotton cover, which M&S markets as a cooler feel for warmer nights. Unlike the deeper Stay Cool 10cm, the whole topper can go in a washing machine at 40°C and be tumble dried on low.

Construction and care

The cooling claim is modest and believable: cotton breathes better than the polyester covers on most budget toppers, and there is no special technology to take on trust. The bigger point is hygiene. Being able to wash the whole topper suits a guest bed, a child’s bed or anyone who sweats at night. If you have a dust mite allergy, note that the NHS advice on allergic rhinitis is to wash bedding at 60°C and above, which this 40°C label does not allow.

It is the most reviewed topper M&S sells, with 352 reviews averaging 4.3 out of 5. As a soft fibre layer it suits a mattress that is slightly too firm, not one that has lost its support.

Sizes and prices

Prices from the M&S product page at the time of writing (October 2026). M&S lists its sizes in feet, and the centimetre sizes above are the UK standard for those beds; there is no small double or emperor. M&S states no sleep trial or guarantee, and its returns policy accepts mattress protectors, the category M&S sells its toppers in, only unopened with the hygiene seal intact.