It has happened two times in my lucids now:
First I become lucid and everything is great but then shortly the light goes away, progressively, and soon I find myself in complete darkness, entirely lost :(. Last night when I still had some light left I asked one of my DCs if he could lit the place up but he didn't respond. Then I yelled something like "INCREASE LIGHTNESS NOW". But it didn't work either... And soon my dreamscape was completely dark and I woke up. :(
Two times now... I need to stop this! Any suggestions?