Cannabis doesn't have a hangover, very indicas can leave you groggy or somewhat high, but that is because you are still some what high, never like a sick feeling though, more like a sleepy hungry feeling.

That is what gets me, too the hangover part, I have smoke some of the best sativas on earth, and one thing they all share is a way less groggy or hangover time than any other bud. Sativas do cause heart racing to some people but the so called hangover is usually a clear normal type life hangover, In other words you become normal faster with Sativas usually no hang over.

By the way you cant get hangovers from weed