Sometimes for me, all it takes is the right amount of sleep then I usually end up having a lucid dream. Perhaps it is that I reach REM or deep enough sleep, then dreaming is vivid enough where I become conscious and realize I am dreaming.

I may have some insomnia, since I do not get really tired until about 1:30am or 2:30am in the morning. However, my amount of sleep can vary from around 5 hours to 7-8, and I have had lucid dreams within all those lengths of sleep.

Its just that there is a distinctive feel (for me) of being in an really vivid dream, and I am even more conscious in these dream states than in others. And these states are usually near the end of sleep, probably in REM. Maybe I could try to keep track of how much I sleep and see if it correlates to lucid dreaming.

Anyway, I just wanted to point out that whenever I get the right amount of sleep, or possibly high quality sleep, I usually end up lucid dreaming.