Breathability depends mainly on the material, not just the shine. Real silk is typically quite breathable and can manage moisture comfortably, which is why many people find it feels less stuffy, especially with a silk pillowcase.

“Satin” can also be breathable if it is made from cotton or viscose, but many satin pillowcases are made from polyester. Polyester usually breathes less and can feel warmer or clammy. Weave density and thickness also matter because a thicker, more tightly woven fabric holds heat more easily. If breathability is your top priority, choose a 100 percent silk pillowcase or a high quality cotton satin, not polyester.