I found an article about a study analysing pleasure responses in brains of people with bipolar disorder vs. people without. The results clearly showed a difference in the levels of pleasure experienced. But note: All of the participants in the study with bipolar disorder were currently in euthymic states (neither depressed nor manic of any level). The article describes this and offers possible reasons for this. See the article at
https://www.medicalnewstoday.com/articles/279338.php if interested.

I'm not sure if this is related to the above, but I have noticed throughout my life that even when I'm clearly stable, sudden exciting events (i.e. a favorite song unexpectedly playing on the radio, great news told to me unexpectedly, seeing someone I adore, but rarely see, winning something, or similar) can make my mood skyrocket. It seems to increase higher than others around me who don't have the disorder, but also experience the same "reward". Then this mood increase lasts for a while, though may or may not go on to be a full episode.

Does anyone else experience this?

[Pookyl]

Yes. As a result if I do something ‘stimulating’ in the morning I have to follow it up with some ‘low stimulus’ activity in the afternoon.

[Unrigged64072835]

I have definitely noticed this! Sometimes I wonder if I was hypomanic again, but then it goes back to normal.

[glennk]

This explains a lot. I've experienced the same excitable pleasure after every car I've bought. I'm up to 13 cars in my 42 years of life.