Why does drinking alcohol make people lighten up?

It is disinhibiting.: Alcohol is a depressant which initially disinhibits people and makes them less likely to feel control over their impulses. Alcohol can impair the ability of the frontal lobe of your brain to help you use good judgment, make rational decisions, plan and organize steps. This is called executive dysfunction. Over time heavy alcohol use can cause shrinkage of the brain and memory problems.