I don't know if it is specifically related to ADHD or Aspergers or a combination of the two.
I think that because our brains are wired slightly different, that the two together is double trouble unless you have coping strategies or support.
I found that with ADHD if you can somehow separate the two, I am one way one minute and another the next.
With meds for ADHD I go into zombie mode and not much fazes me and I am left feeling angry or empty. Neither of which are a great help in day to day life.
I will give you an example of my mood shifts (I don't like to use the word swings!):
I went to practice today and spent an hour trying to get the EQ right and it just wasn't working so I get angry and leave with two hours of time paid for.
My partner said some things that touched a nerve all the way home, and into the house, and now I am feeling like s**t.
The worst part of it is that I want to be happy right now, but I am feeling really drained and my partner is feeling drained from me. But I am just so fed up of saying sorry to everything that I do, it would be nice if someone said it back and shouldered the "blame" once in awhile.
Ok so if this is what you are referring to or just a change for no reason that you are aware of?
For me it's the small things that add up into one big thing and then I explode like a volcano!
Everyone is different and it's hard to just be when you have so many obstacles in the way that NT's can seemingly breeze through.
I have rambled I have!