When the nervous system detects the body overheating, it responds by changing breathing and blood flow patterns, causing a person to sweat as a cooling mechanism. Sweat can happen anywhere in the body, but is generally associated with the armpits, hands, feet and face. Research at the Mayo Clinic suggests excessive facial sweating, or facial hyperhidrosis, affects about 2.8 percent of Americans. It can be very uncomfortable, interfering with daily routines and social activities.
Excessive facial sweating is said to be primarily dependent upon genetics, according to the website, Excessive Sweating Info. In fact, a human being has between two and four million sweat glands in the dermis layer of skin. The amount of glands and their particular location is directly related to heredity. In other words, if you have facial hyperhidrosis, it is highly likely that another member of your family has a large number of active sweat glands in the face and scalp as well.
Irregular Brain and Nerve Activity
The sympathetic nervous system, which is part of the autonomic nervous system responsible for "defending" the body from danger, instructs the brain to turn sweat glands on and off depending on environmental conditions. When a nerve does not function properly because of Syringmyelia or another nerve-related disorder, the nervous system sends mixed signals to the hypothalamus which controls sweat glands, hunger and thirst, resulting in excessive sweating of the face. Similarly, emotions, such as depression, stress and anxiety, can alter nerve activity in the hypothalamus, causing confusion and allowing for sweat gland over-activity for the same reason.
Overweight people tend to sweat more than slim people because the body stores a surplus of minerals, which the sweat glands then have to excrete. The more fat you have stored on the body, the greater the amount of excess facial sweating. Of course, individual differences will depend largely on genetics.
Exercise and Excessive Heat
Exercises, such as running or lifting heavy weights, can cause the body to overheat leading to excessive facial sweating. Any kind of strenuous exercise or exposure to extreme heat, or hot weather, can produce excess sweat because it helps the body cool off. Sweating without the presence of body heat, nervousness or being overweight may be cause to see a doctor.