Yes, stress does cause hair loss. Here are some of the common instances:

1. A sudden physical or emotional stress can cause the hair follicles to prematurely enter the catogen (resting) and then the telogen(falling) phase. The hair takes about three months to pass through these phases and then falls out. Normally, it should have been in the anagen(growing) phase for about a year before going into the catogen phase. So, if you were worried about something three months ago, and notice your hair is falling now, you know what the cause is. In most cases the hair loss is temporary and the hair soon recovers.

2. More serious is Alopecia Areata, which is an auto-immune disorder where our immune system mistakes our hair follicles for foreign bodies and begins to attack them. The result is that you begin to go bald in patches. This kind of reaction can be brought about by Stress.

3. Stress can interfere with your hormonal cycles and because your hair is affected by changes in blood content, you will notice a change.

4. A severe shock might even cause rapid graying called "Overnight Greying". Thus, if you can trace hair fall to a stressful event in the recent past, remember not to worry too much or you could only worsening the situation. But if your hair loss persists, don't hesitate to contact a trichologists.