I've done it before. I've taken a nap this afternoon, I got the SP in my hands, didn't continue though. It felt like they were about to fly away. Scary shit...

I think that naps are different so you don't have to "wait for REM" for 90 minutes. What you should also know is that experienced LDers can WILD at will, no need for all that waiting. But these usually have a lot of dedication and training .