If you wake up with knotty, frizzy hair, your pillowcase might be the culprit....

https://www.pfdbookmark.win/sleeping-on-cotton-creates-friction-which-often-leads-to-unwanted-breakage-a

If you wake up with knotty, frizzy hair, your pillowcase might be the culprit. Standard cotton creates friction that snags delicate strands overnight