Cotton pillowcases create friction, leading to morning frizz and breakage....

https://www.bookmarkpage.win/waking-up-with-knotty-hair-your-cotton-pillowcase-creates-friction-that-leads

Cotton pillowcases create friction, leading to morning frizz and breakage. Switching to silk is a simple fix, but if you’re not ready to swap your bedding, try a loose, soft scrunchie braid