If you wake up with knotted, frizzy hair, friction is likely the culprit....

https://bizzmarkblog.com/do-i-need-silk-to-reduce-frizz-or-can-i-just-change-my-habits/

If you wake up with knotted, frizzy hair, friction is likely the culprit. Cotton pillowcases can snag delicate strands, unlike silk which lets hair glide