However, your post caught my eye because I was recently diagnosed with
Narcolepsy with Cataplexy. Often in people who have this disorder, they experience loss of muscle tone which presents similarly to fainting after experiencing emotion (anger, excitement, surprise, laughter). In my case, I thought I was having fainting spells, but was actually experiencing Cataplexy, which is when your body actually abruptly enters a REM sleep cycle.