Feeling grumpy is good for you.

From BBC:

In a bad mood? Don't worry - according to research, it's good for you.

An Australian psychology expert who has been studying emotions has found being grumpy makes us think more clearly.

In contrast to those annoying happy types, miserable people are better at decision-making and less gullible, his experiments showed.

While cheerfulness fosters creativity, gloominess breeds attentiveness and careful thinking, Professor Joe Forgas told Australian Science Magazine.

The University of New South Wales researcher says a grumpy person can cope with more demanding situations than a happy one because of the way the brain "promotes information processing strategies".