air loss caused by severe emotional stress

Some people experience Telogen Effluvium or sudden diffuse hair loss after a traumatic event such as the death of a family member or someone close, an accident, abuse or any other severely traumatic event. These events may trigger hair follicles to enter the resting phase prematurely in which case an increase in the amount of hair shed will be noticed about 3 months after the event, as the hair makes a transition from the
The above types to sudden hair loss are usually temporary an in most cases hair will grow back normally soon after it has fallen out.

I am inclined to think this is not meant to be taken literally, but in the event that it is, there seems to be a distinction between hair thinning (hairs come out on the brush or comb individually; I would think "diffuse" hair loss is also of this kind), and hair shedding (hair comes out in tufts or clumps).

Hair Loss -- Symptoms
Hair loss can occur as thinning, in which you may not notice hair falling out, or as shedding, in which clumps of hair fall out. ...
www.webmd.com/hw/hair_loss/aa151683.asp

She is so anxious about her son's success that she is losing great clumps of hair. She is obviously extremely anxious about her son's success. It might be true that she is experiencing significant hair loss. On the other hand,it might be an exaggeration. Whether or not it is true doesn't matter. It is how the woman chose to express the intensity of her anxiety.