What happened / what is this "transition"

I did a WBTB, took my LDS and fell asleep. I caught myself waking up and told myself not to move. I did nothing. About 30 seconds after this I felt like there was an earthquake, I saw very BRIGHT red and green flashes. This lasted about 10-15 seconds. I felt like i was on a roller coaster. But, nothing happened after that. I stayed calm and did not talk to myself while this was happening. (except for the initial oh shit whats happening)

So, was I transitioning into my dream state? If so, what did I do wrong? I remember just letting it rock me and hit me hard. I almost woke myself up because the vibrations were so strong... it was more like someone pushing me back and fourth.

I've had this feeling 3x since starting my LDing. Each time I feel closer to a LD but it ends up failing.

I ended up having 2 successful LDs after this occurred.

Any advice is appreciated.

Haha same thing happened to me this morning with my LDS. I actually woke up from two FAs and stayed still. Started hearing all these people talking and songs playing haha. Then I started floating up and then it stopped. Nothing happened. I think maybe it was because it was the end of my rem period. God, I got into SP so many times this morning. I constantly floating and spinning.

I think you were very close to an OBE which usually starts like that sometimes called hipnagogic state or transition between being awake and falling asleep. I think those people who master the WILD technique will have a lot more to say.