If you get tired find a place to park and take a hour nap log it as Safety Break 392.3 they won't discipline if they do threaten to make a complaint to OSHA! It has taken me a few times almost 14hrs just to go from 211 to 309 if you're on extra board don't have set sleep schedule or they let you rot at the hotel too long.
Section § 392.3: Ill or fatigued operator.
Section 405 of the Surface Transportation Assistance Act of 1982 (STAA) (49 U.S.C. 31105) states, in part, that no person shall discharge, discipline, or in any manner discriminate against an employee with respect to the employee’s compensation, terms, conditions, or privileges of employment for refusing to operate a vehicle when such operation constitutes a violation of any Federal rule, regulation, standard, or order applicable to Commercial Motor Vehicle (CMV) safety. In such a case, a driver may submit a signed complaint to the Occupational Safety and Health Administration.