I have been going to Uman for Rosh Hashanah for the past few years and a few times I have a night of shaking panic attacks lying in bed.
The first time was on Rosh Chodesh Elul about ten years ago when I was in bed shaking all night long. I was at home at the time.
I asked a Rov about it and he told me that it is brought in seforim that it can happen on that date. Apparently there is a sort of shakeup in Shamayim on that date and your neshama feels it!
The next time I was in UMAN a day or two before Rosh Hashanah and the same thing happened I was in bed and started shaking for 2 hours.
The next time was 2 nights ago when the same thing happened – I am due to go to Uman next week please G-d, and think it is fear of the trip or fear of the day of Judgement!