Tics have no apparent purpose. They are not voluntary, but the person may be able to control them for short periods. Repressing them usually makes the person anxious until he or she develops another tic. They usually cease during sleep. They become more pronounced with tension and emotional strain.
Some tics start as true spasms.
Tourette's syndrome is a rare condition that begins in childhood. One may see blinking, grimaces, shrugging, and arm movements. The tics get worse and are joined by vocal tics. There may be grunting, sniffing, or barking noises. The person is prone to sudden and loud swearing.