Cotton pillowcases cause friction that snaps hair. While silk helps strands...

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

Cotton pillowcases cause friction that snaps hair. While silk helps strands glide, you don’t need an expensive upgrade. Try a loose plait or silk scrunchie to secure your ends before bed. It’s an easy way to wake up with less frizz.