Teeth grinding is generally caused by psychological factors such as emotional stress or nervousness. Long term teeth grinding will damage the enamel and expose the dentine causing sensitive teeth.
To stop teeth grinding, the cause must be identified. If teeth grinding is severe, you should go to a dentist as soon as possible. The dentist will give appropriate treatment such as fabricating a "Mouth guard" to keep the teeth from further attrition.
To relieve teeth grinding, one should keep relaxed, and should have sufficient sleep and exercises to relieve stresses from daily life.