8 of the Worst Things You Can Do to Your Hair

Turns out the tip about sleeping on a satin pillow case isn't just some mane marketing ploy. "Sleeping on cotton pillowcases causes frizz and split ends," says celebrity stylist Cynthia Alvarez. It also soaks moisture out of hair. "Yes, it's soft and durable, but rubbing your hair against it is a bad idea. Use a satin or silk pillowcase instead," Alvarez suggests.