Bruxism when the parafunctional activity occurs – during sleep ("sleep bruxism"), or while awake ("awake bruxism"). This is the most widely used classification since sleep bruxism generally has different causes to awake bruxism, although the effects on the condition on the teeth may be the same. The treatment is also often dependent upon whether the bruxism happens during sleep or while awake, e.g., an occlusal splint worn during sleep in a person who only bruxes when awake will probably have no benefit. Some have even suggested that sleep bruxism is an entirely different disorder and is not associated with awake bruxism.
Bruxism who have sleep bruxism are more likely to also have sleep bruxism than children of people who do not have bruxism, or people with awake bruxism rather than sleep bruxism. Certain stimulant drugs, including both prescribed and recreational drugs are thought by some to cause the development of bruxism, however others argue that there is insufficient evidence to draw such a conclusion. Examples may include dopamine agonists, dopamine antagonists, tricyclic antidepressants, selective serotonin reuptake inhibitors, alcohol, cocaine, and amphetamines (including those taken for medical reasons). In some reported cases where bruxism is thought to have been initiated by selective serotonin