Hi ,
That's a great question. I found this quote that I thought said it well:
"Even among people who do not have Parkinson’s, it is commonly believed that every body is different every day, affected by so many factors—from how much sleep we got, to how stressed we are, to how much we hydrated the day before.
Granted, living with Parkinson’s means that the swings between the good days and bad days can be much bigger. Even during the day, it can be common for some people to feel their best just after waking from a full night of sleep and then they struggle the most at the end of the day, when energy is lowest."
Taken from: https://parkinsonsdisease.net/living/hardest-part
Additionally, I thought you may find this article helpful as well: https://parkinsonsdisease.net/living/managing-mood-changes
All the best,
Christina, ParkinsonsDisease.net Team