We found that among young recreational cannabis users, a regular dose of cannabis had no effect on simple and learned tasks, but its use led to significant impairments on complex and novel driving-related tasks, as well as perceived driving ability and safety, for up to 5 hours after use. The present finding that the first 5 hours after cannabis use affected driving-related performance substantiates the recommendations of Canada’s Lower-Risk Cannabis Use Guidelines, which recommend waiting 6 hours after cannabis use before driving.30 [7]