How does alcohol cause hangovers?

The molecule responsible for hangovers is ethanol, which we colloquially refer to as alcohol. Ethanol is present in all alcoholic beverages, and generally speaking, the more ethanol, the greater the potential for a hangover. So, how exactly does alcohol cause a hangover— and is there any way to prevent one? Judy Grisel explores the surprising ways that alcohol affects the body. [Directed by Anton Bogaty, narrated by Alexandra Panzer, music by Jarrett Farkas].