A mood swing is simply a noticeable change in one’s mood or emotional state. Small mood swings are a part of most people’s lives.

We get happy, we get sad. We can feel on top of the world, and then later in the same day, we feel tired, lethargic, and beaten down. However, some people’s mood swings can be so extreme, sudden, or serious that they interfere with that individual’s functioning in everyday life. 

The best example of a disorder characterized by mood swings is bipolar disorder—from manic to depressed. However, a person can have mood swings between any two moods or emotions—sad to angry, happy to contemplative, and so on.