TRB’s Commercial Truck and Bus Safety Synthesis Program (CTBSSP) Synthesis 19: Effects of Psychoactive Chemicals on Commercial Driver Health and Performance: Stimulants, Hypnotics, Nutritional, and Other Supplements identifies available information and research gaps relating to the use of chemical substances by commercial drivers and is intended to provide up-to-date information to inform decision makers about the near-, mid-, and long-range planning needs for research and educational outreach programs.