"Stress doesn't really have any effect on your hair."
The good news is that excessive physical or emotional stress hasn't been proven to make hair turn gray—or curly or frizzy, for that matter. The unfortunate news is that it could cause hair to fall out. Major stressors such as illness, injury, surgery or the loss of a loved one can affect your hair's growth in two different ways: The hair might stop growing and lay dormant, then fall out several months after the life-upending event (it will grow back in half a year or so). Or, it could stimulate the white blood cells to attack the hair follicles, causing the hair to fall out in patches (this may require special treatment by a doctor). In both cases, the hair loss isn't usually permanent.