Excessive hair loss can occur for a variety of reasons. In some individuals, hair loss occurs after an event that causes severe psychological or physical stress. This type of hair loss usually occurs more than several weeks after the stressful incident that precipitated the hair loss. Although the loss of hair — particularly in women — can be upsetting, your hair will usually return to its normal thickness as new hair replaces the lost strands.

Hair Cycle

Although the rate and pattern of your hair growth may vary, most individuals have approximately 100,000 strands of scalp hair and lose approximately 100 of those hairs each day. This rate of loss would eventually result in complete baldness, but normally new hairs grow to replace the lost ones. Individual hair strands usually survive about 4.5 years and grow an average of one-half inch each month.

Conditions

Hair loss due to stress includes three conditions: Alopecia areata is hair loss due to white blood cells attacking the hair follicles, a possible result of severe stress; telogen effluvium can occur when physical or emotional stress causes large numbers of hairs to enter the resting phase, the stage before the strands fall out; and trichotillomania also results in hair loss, although this condition involves an irresistible urge to pluck hair strands out of your eyebrows, scalp and other areas. MayoClinic.com advises that this behavior can be due to stress, loneliness, frustration or anxiety.

Causes

Your response to stress, known as the fight or flight reaction, is your body’s way of protecting you against threats to your safety. Unfortunately, stress can increase your risk of a number of disorders including heart disease, obesity, memory impairment and depression, as well as temporary hair loss. The causes of stress may include severe infections, psychological stress, major surgery, crash diets, high fevers and childbirth.

Outlook

A shock to your system may cause large amounts of hair loss about two months after the precipitating event. According to the American Osteopathic College of Dermatology, shedding may decrease after six to eight months. Managing your psychological stress can help minimize your chances of stress-related hair loss.

Precautions

While stress may cause a sudden increase in the number of hairs you shed each day, other health conditions may also contribute to hair loss. Talk to your doctor if you notice an excessive amount of hair in your brush or shower. Other possible causes for your hair loss include autoimmune conditions, thyroid diseases, ovarian tumors and ringworm of the scalp. While stress may be responsible for your condition, your doctor can help rule out other possible causes of excessive hair loss.