The euphoric feeling I experienced was relatively mild. For me it was just happiness and an elevated sense of well-being. When a person has euphoria, the way they feel does not reflect the reality of their situation.

For example:
Being on the verge of losing my eyesight wasn't a good situation. However, I didn't care if I ended up blind in one eye because overall, I felt great.

Not sleeping for days was a good thing because I felt like I was being productive. I would do things just for the sake of doing something ... I didn't care if what I did was useful or not. I literally felt like sleep wasn't necessary.

I wasn't manic but I definitely had hypomania.

"Hypomnia is characterized by elevated mood in addition to behavior change including increased energy, increased confidence, increased activity, impulsivity, irritability, disinhibition, and a reduced need for sleep."
https://www.mayoclinicproceedings.org/article/S0025-6196(11)61160-9/fulltext
I wasn't aware of any of this when I was first diagnosed with PMR and started taking prednisone on a long term basis. I have done a retrospective review of my own behavior because I wasn't aware that something wasn't quite right in the beginning. Sadly, many people never become aware of what prednisone does to them

The body has a complex regulatory system. The cortisol our body produces plays a huge role in how our bodies function and maintain homeostasis. When we take prednisone, we basically tell our bodies that we can manually control how we function. We take the entire system out of autopilot and hope we can manage things under the guise of "managing inflammation."