Biphasic curve

The biphasic curve for alcohol consumption represents the changing effects of increasing blood alcohol concentration (BAC) on the typical person who has not developed alcohol tolerance.

People typically report that consumption of an alcoholic beverage results in pleasurable effects. They tend to feel better and experience a positive emotional state. They generally assume that if consuming one drink makes them feel better, then they will feel even better with each additional alcoholic beverage drunk. However, this is correct only to a point.

The positive effects from consuming alcohol tend to increase until a BAC of about .055 is reached. After that point, increased BAC tends to lead to increased negative effects.

Source

 * How Alcohol Effects Us: The Biphasic Curve