"Can a bipolar person go from being happy one minute," a reader asked, "to irritable the next, and angry 20 minutes later?"
The short answer is yes - such changes can happen just that fast. But think about it - a person who doesn't have a mental disorder can change that fast, too.
Here's a hypothetical example: Lauren is at a party, having a good time. Then she overhears someone say something nasty about the hostess, who is Lauren's best friend. Instantly irritated, Lauren is short with the next couple of people she talks to while the remark preys on her mind, and 20 minutes later she confronts the speaker, yelling at him.
Lauren may have a hot temper, but she doesn't have bipolar.
That said someone with bipolar disorder might be more likely to have this type of quick emotional shift. It's less likely to be an actual change of mood - that is, a switch from mania or hypomania to irritated depression - as it is to be a change of emotional symptoms within a manic or hypomanic state.
In my SharePost Mania vs. Hypomania I pointed out that both extreme happiness and anger, irritability and hostility are possible symptoms of both these moods. This means it may be very easy from someone who's in a manic or hypomanic episode to make a fast switch from one state to another.
What the original question doesn't tell us is how long the happiness had lasted before the shift, and what happened afterward. It's also possible for this change to be a quick switch from one bipolar mood to another. Irritability can also be a symptom of bipolar depression, so if other depression symptoms appeared after the emotional change, a new episode may have begun quickly.
Do your moods and/or emotions, or those of someone you care for, change quickly?