Sweating, also known as perspiration, is a process in which many organisms, including humans, release water and dissolved salts through pores in the skin. The primary purpose of this process is thermoregulation, or temperature control; an organism tends to sweat when it becomes overheated. Most causes of sweating are related to returning the body to a healthy and normal temperature. Many organisms tend to sweat when they engage in some form of vigorous activity, such as intense exercise. There are many other things that can cause sweating, though; some are related to medical disorders while others can simply be related to stress or emotional strain.
Vigorous physical activity is among the most common causes of sweating. When one sweats, perspiration covers the skin; this perspiration later evaporates and takes some of the body's heat with it. When one engages in particularly hard exercise, his body produces more heat. Accordingly, the amount that one sweats corresponds to the rigorousness of the activity he is engaging in.
Causes of sweating also tend to be closely related to the balance of hormones in the body; conditions or substances that alter hormone levels can cause sweating. People who suffer from cancer or some infections sometimes sweat because of the effects such illnesses have on the balance of hormones. Fevers are also among the many causes of sweating, but this is more closely related to an increase in body temperature than to hormone balance. There are some substances many people ingest on a regular basis that can cause sweating. Caffeine and alcohol are two of the most prominent examples, though many medications can have similar effects.
There are also some psychological causes of sweating. People often sweat when they are scared, nervous, or under significant stress. This is also related to hormones; when one is under emotional stress, the adrenal glad produces more than normal amounts of the hormone epinephrine. This, combined with other altered hormone levels, can lead to sweating. Often, sweat in response to psychological stress feels cold because it does not occur in response to physical heat.
Some people sweat excessively almost all the time. Such excessive sweating is known as diaphoresis or hyperhidrosis, and it often has no clear cause. Usually, this form of sweating is focused in the palms of the hands and in the underarms. Because it can smell and soak through clothing, this can often be an embarrassing condition.