Which phrase best captures the concept of unpredictable mood swings?

• A. Stable mood
• B. Anhedonia
• C. Mood lability
• D. Flat affect

Answer: (C)

Mood lability describes rapid, unpredictable shifts in mood. When someone is mood labil, their emotional state can swing from happy to sad, irritable, or anxious in a short span and often with little or unclear triggers. This instability is what people mean by unpredictable mood swings, and it’s a term clinicians use to capture that dynamic of changing affect over time.

This is distinct from a stable mood, which stays relatively even; anhedonia, which is a reduced ability to experience pleasure, and flat affect, which is a lack of outward emotional expression. Mood lability focuses on the frequency and unpredictability of mood changes themselves, not on the absence of emotion or the inability to feel pleasure.