This is likely due to the comfort layers up top, which are made with high-density memory foam ... every mattress we recommend on this list is made without fiberglass. We checked fiber content ...

The format of the fill is also important: Shredded or chopped foam will allow for more airflow than a solid slab. Alternatively, a fiber mattress topper filled with cotton or polyester can add ...

Adding a topper to your mattress ... (that's not foam), consider Saatva's Down Alternative Featherbed Mattress Topper. It's filled with hypoallergenic down and lyocell fiber and is soft enough ...