¿How long can a lucid-dream be?

¿Is there any point where, no matter what you do, you have to wake up, and even if you resist with all the techniques you know, you’ll still wake up?

¿Do any of the lucid-experts remember when they wake up, or is it too “blurry”?

I’m just wondering, because if there is no point like that, wouldn’t it mean that if you continue lucid-dreaming, you’ll sleep longer?

Ofcourse there’s a point where you wake up.
Otherwise you could sleep until you die of thirst or hungry

During each sleep cycle, which lasts roughly for 1.5 hours, there is some time reserved for deep delta sleep. During this period (also called nREM stage 4), there is no dreaming, because the mechanism behind it is shut down. So, theoreticaly 1 dream can last from the end of deep sleep till the start of the next one.

I usually get to a point where I just feel myself waking up and I want to write down the dream, rather than try and go back to sleep, in case I forget it. If I have really long dreams then I have trouble remembering parts of it so it might as well have been a few different dreams.

It would be very hard to continue a lucid dream as long as you want, even if you could continue the dream into NREM sleep, because you’d get thirsty and stuff and have to ignore it.

I’m getting to believe that dreaming is possible anytime independently of the brain actual state. It’s all about remembering that may be impaired when REM is held off. Sometimes when I got myself to dream in the early cycles I have the impression that I’m just connected to an ongoing activity. It seems to me that the very same dream could be remembered within a span of couple of days, piece by piece yet it remains a continous experience situated somehow outside of linear time.

I think you’re right Popov in thinking that we possibly always dream. I guess it’s kind of like 2 processes going on, dreaming and waking, “battling” for priority. During waking the wake senses and wake consciousness have the upper hand (normally), but when these outward senses shut down, internal events get the upper hand (dreaming), unless these are shut down too (deep delta sleep). This explains why we have dreams in REM, in non-REM, and sometimes even during the day (daydreaming). It also is proved that REM increases memory neurotransmitters (ach), so that during this period we remember more dreams, which might create the illusion that we really dream more during REM.