Waking up with a bird’s nest? It’s often the friction from cotton pillowcases...

https://theaustralianpost.com.au/protecting-hair-while-sleeping/

Waking up with a bird’s nest? It’s often the friction from cotton pillowcases causing that morning frizz. Switching to silk reduces drag, but the real difference is popping your hair into a loose silk scrunchie or a relaxed plait before bed