Bruxism bruxism), but also possibly grinding, and is often associated with other semivoluntary oral habits such as cheek biting, nail biting, chewing on a pen or pencil absent mindedly, or tongue thrusting (where the tongue is pushed against the front teeth forcefully). There is evidence that sleep bruxism is caused by mechanisms related to the central nervous system, involving sleep arousal and neurotransmitter abnormalities. Underlying these factors may be psychosocial factors including daytime stress which is disrupting peaceful sleep. Sleep bruxism is mainly characterized by "rhythmic masticatory muscle activity" (RMMA) at a frequency of about once per second, and also with
Habitual aspect The habitual aspect is a type of imperfective aspect, which does not depict an event as a single entity viewed only as a whole but instead specifies something about its internal temporal structure. Östen Dahl found that the habitual past, the most common tense context for the habitual, occurred in only seven of 60 languages sampled, including English. Especially in Turkic languages such as Azerbaijani and Turkish, he found that the habitual can occur in combination with the predictive mood. Standard English has two habitual aspectual forms in the past tense. One is illustrated by the sentence "I used to