Telogen effluvium is a scalp disorder which presents by thinning and shedding hair.  This illness is considered the second most common cause of hair loss.  This is a reversible hair loss condition, usually prompted by stress, or a stressful experience.  This stress can alter the regular hair cycle causing this condition. The condition is named after the mechanism in which the hair loss occurs. That is, hair loss happens from the early entry of the hair into the telogen, or resting, phase of the hair follicle.