Dermatologists say that although life's normal ups and downs aren't enough to precipitate it, women can lose up to 50 percent of their hair after an unusually stressful event. Dr. Rebecca Euwer, a Dallas-based dermatologist, said that some of the more common causes are childbirth, surgery or a death in the family.
"When someone comes in and says they're losing their hair, you ask, 'Well, what happened about three months ago?' " Euwer said.
This type of hair loss can occur both in men and women. But most of the known cases are reported by women.Euwer said hair goes through three phases: growing, resting and falling out.
About 90 percent of hair is in the growing phase. Most of the remaining hair is in the resting phase, where it remains for about three months. When people suffer physical or psychological trauma, it shocks the hair follicles into a resting phase.
People do not notice the effects until three months later, when it begins to fall out.
"About 1 percent of your hair is falling out, so it's normal to lose about 100 hairs a day," she said. But when you begin to notice more hair on your pillow or in your shower drain, it's time to go to the doctor, she said.
The good news is, it will usually grow back on its own.
However, there's a chance that women older than 30 could be experiencing the female equivalent of male-pattern baldness. Euwer said if this is the case, only hair on top of the head will thin. If it is stress-related, the sides and back of the scalp will also be affected.
Then there are women hit with the double-whammy: both stress-induced hair loss and natural thinning with age. In these cases, doctors might need to prescribe Rogaine, an over-the-counter hair regrowth treatment.
But Euwer said to use this with extreme caution. Some women have gotten more than they bargained for after using extra-strength Rogaine, which is intended for men.
"Women who get hold of that have gotten some on their forehead," she said. "Then they have to go and get laser hair removal."
Not all hair loss is stress- or age-related. Excessive styling or harsh treatments can also damage the hair, causing it to fall out. And a sudden loss of hair may signal a more serious condition, such as diabetes or lupus.