isolation

(A) means any instance in which a youth is confined alone for more than 15 minutes in a room or cell; and

(B) does not include—

(i) confinement during regularly scheduled sleeping hours;

(ii) separation based on a treatment program approved by a licensed medical or mental health professional;

(iii) confinement or separation that is requested by the youth; or

(iv) the separation of the youth from a group in a nonlocked setting for the limited purpose of calming;