stages of sleep

i have read a little about stages of sleep but i wouldnt say i know alot about it, on some occasions i have just became lucid in my dreams and i wake up in the morning, thats it, no problem.

however, i find i have become lucid more often when i have went back to sleep in the morning after waking up for a little while, is this because im more aware of what i want to achieve when i go back to sleep?

why is this? am i not getting enough sleep at night and just waking up to early before REM kicks in and not giving myself a chance to become lucid? or am i not even making sense?

basically what im asking is do i have to sleep longer than normal to achieve lucid dreams?

i have heard about the wake back to bed technique, is this what im basically doing without knowing it?