Physical or emotional stress can trigger hair loss whether people are predestined to lose hair or not. When stress causes hair loss in women who do not have hereditary hair loss, the effects are usually not permanent; but in women who do have hereditary hair loss, stress can actually speed up the process. The stress experienced must be quite severe before it leads to hair loss. Examples of severe stress are loss of a loved one, strenuous sports, training, severe illness, drastic weight loss, surgeries and emotional stress. The body simply shuts down production of hair during periods of stress since it is not necessary for survival and instead devotes its energies towards repairing vital body functions. You may notice excessive hair shedding 4 weeks to 3 months after an illness, surgery, high fever or sever flu.
Another type of ‘reactional hair loss’ that can occur is in women that have recently given birth. At about the sixth or seventh month of pregnancy , the fetus starts developing its own hair. For this it uses a significant portion of its mothers amino acids. Consequently between 3 months and 1 year post childbirth, the mother will experience a significant loss of hair.
These conditions cause hair to shift rapidly into a resting phase, meaning you will see less new hair growth. A normal amount of hair typically will appear after the growth phase resumes. This means that the total hair loss and re-growth cycle can last 6 months or possibly longer when induced by physical and emotional stress.
There are other health conditions which may go undetected that can contribute to hair loss. This includes anemia, low blood count and thyroid abnormalities. Both of these conditions can be detected by a simple, inexpensive blood test.