So, what was *that*? Weird WILD experience, please help!

Recently I've been attempting to WILD, about 2 times a night (once when I go to bed, from "cold" and again when my alarm wakes me up for WBTB). Last night I stayed up later then usual so I was tired and awake when I was usually in REM so that, hopefully, my WILD had a better chance of being successful. I was in bed for about 15 minutes (maybe longer) when my heart started beating really fast. Its never done this before. Then my body started to go numb so that I couldn't tell where my fingers ended or my chest began - like I just melted into a giant blob. Then my eyes started to flicker really fast and I couldn't stop it and it felt like my eyelids where glued shut. Now, I wasn't panicking in any of this, I thought it kind of strange that my heart was beating so fast but I wasn't nervous or scared. This went on for about 5 minutes, then it just faded away. My heart rate went back to normal, I could feel my arms and legs again, my eyes weren't moving uncontrollably - normal. So, what was it? Because I have no idea. TL;DR: tried to WILD, heart rate went up and body went numb but then nothing happened. What was it? *EDIT: After rereading this post I think I went through kind of a sleep check from my brain but then got too excited and ruined my chance for a successful WILD. Lesson learned - calm down.