Are you being treated with Zyrem? Have you ever been told you have a drop in blood pressure when you stand up (POTS).
If neither of those is the case, then there does need to be some explanation for this and then some precautions taken so you are not injured if you fall.

I have a drop in BP the neurologist & my Dr's tell me it's not cataplexy. I have had those spells going on 10-12 yrs.they were few & far between until the last 3-4 yrs often I can catch myself & sit on an arm rest or the bed if not I drop instantly hurting my ankles my full body weight lands on them any way they happen to land or bend! It's so painful, I hate it! I have hit my head fell off my bed i woke to go to the bathroom & fainted I face planted in my floor had a huge black eye. I fell off the arm rest of the couch & hit the cat tower, had a reverse shoulder replacement from that. Using a walker w/a seat helps if I know i am going to faint but if I just faint I am unable to grab & hold on. About a yr ago I fainted & crawled to my walker up on my knees I went out again & my chin hit the plastic seat & I bit clear through my bottom lip. My Daughter had me in a wheelchair until I got to the hospital. I was in for a week after Thanksgiving @ that time they started me on Midodrine 2.5 mg I take it a few times a day it helps alot!
They took away all of my blood pressure meds & anything else that could cause a drop in BP. In the past i would have repeated spells daily or go a year w/o having them. I was so relieved when I read your post!! Not that misery loves company but... I'm not alone! I have Narcolepsy only. My spells happen when I sit up or stand up my BP drops excessively low. I can start to fall & can't catch my self to stop, my arms wouldn't work to save my a**! It's so darn frustrating!!

No to the Zyrem, my Dr has me on Modafinil and I have low blood blood pressure as normal readings, or did till the chronic pain. But I've never felt anything like that before.

I'm going to talk to him the next time I see him. I know he originally said narcolepsy without cataplexy but maybe he missed the cataplexy cause as I said I've never gotten right up to move after.

Usually excitement sneeze will make me loss muscle control it sounds
like cataplxy ask your neurologist hope you can figure this out God bless