Causes for Excessive Perspiration

Hyperhidrosis is excessive sweating. Hyperhidrosis is defined as the production of 100mg of sweat in the axilla over 5 minutes. The human body has 2-4 million eccrine sweat glands which function to cool the body by perspiration.

Innervations of these sweat glands are from the hypothalamic preoptic sweat center in the brain through brainstem and medulla. These nerves then enter the spinal cord and synapse in the anterolateral cell column of the spinal cord. These neurons subsequently exit the spinal cord and enter the sympathetic ganglia in the chest and finally supply the upper limbs.

It is thought that the over stimulation of the sweat glands in hyperhidrosis is related to the over activity of the sympathetic nervous system. Perspiration or sweating can be induced by emotional stress of thermal stimuli.

Emotional sweating is more common in the hands, underarm and feet. Subsequently emotional sweating or perspiration stops during sleep but thermal sweating can occur during sleep.