Features
Mattress Cooling: What Actually Matters?
Cooling is not a single material or badge. It is the result of several layers plus the sleep environment.
Construction factors
Open spring cores can allow airflow, while dense comfort foams may retain more heat depending on formulation and how deeply you sink.
Outside the mattress
Sheets, protectors, comforters, pajamas, room temperature and humidity can strongly affect perceived sleeping temperature.
For one brand-specific example, see Aviya cooling design.