No, Cocoon by Sealy does not have fiberglass. Instead, it is made with Cocoon Chill technology, which is a fabric layer that has a combination of cooling and supportive foam layers, designed to keep sleepers cool and comfortable. The mattress also has a breathable, stretch-knit cover that helps wick away moisture and promote airflow. Additionally, the mattress is CertiPUR-US certified, meaning it does not contain any toxic materials like formaldehyde, heavy metals, or ozone depleters.