Night sweats, a common perspiration disorder, often accompanies different kinds of diseases. They occur during sleep and stop upon waking. Perspiration is how the body regulates its temperature. It's controlled by the sympathetic nerves thus increases when the nerves become excited. The quantity of sweat and the speed by which it is expired through the body's 200-500 million sweat pores depends on environmental conditions such as temperature, moisture and wind, as well as a person's health: physical strength and emotional status. A healthy person produces between 500 and 1,000 cc of sweat each day. A person with a perspiration disorder will produce much more.