Cotton pillowcases cause friction, leading to breakage and frizz. Swap to silk...

https://www.4shared.com/office/pcYDzaBAjq/pdf-88397-12006.html

Cotton pillowcases cause friction, leading to breakage and frizz. Swap to silk for a smoother surface, or braid your hair into a loose, low plait before bed. It’s an easy habit that keeps your hair healthy and makes your morning routine much simpler.