I tend to be in either an emotional whirl wind or zoned out state
So that would be your baseline. AKA your own personal version of normal (for right now) & your minimum starting off point.
Conversely, If your normal is usually different? The fluctuating back and forth from emotionally volatile vs disassociation would be a departure from your baseline.
In part it very much depends on how long you make the arc. If my arc is the past 5 years? Then my baseline is XYZ. If my arc include the past 15 years? Then the past 5 years is a departure from my baseline of ABC. If I shrink my arc to the last month? Or the last day? Then we see even more variation. If we want to change my baseline ________? Then we're working on changing what my normal ________ is. Whether that's my emotional state, or heart rate, or any other thing we choose to focus on.
Example, if an ambulance comes and takes your baseline heart rate? That tells them what your heart is doing
right now. Any departure from that, up or down, gives them more info. Your baseline heart rate can be a bloody mess, and it needs to be stabilized. Once it is stable? That's a new baseline. If it's all over the place and can't be stabilized? That's still your baseline. Your baseline heart rate can be steady, and that let's them know that any departure from that needs to be stabilized.
It's just a subjective tool to measure normal, or right now, or where we're starting from... So we can compare it to other things.