A few nights ago, I had a kind of normal dream. I was talking to my friends about physics stuff, and the conversation slowly changed to mathematics. Now some of you might know I memorised Pi to slightly over 140 decimal places back around 2007-2008. I have some intention to continue, although, as I have realised, it's about 14 times the usual required precision by most engineering standards. I do it out of pure fun and awesomeness. There's only one guy whom I know personally who memorised Pi beyond 5 decimal places, but he didn't even reach 100 (I think it was around 50+). Competition is far and few...
Anyway, so with the conversation geared towards mathematics, naturally, Pi had to pop up somewhere, and I decided to rattle it off like I normally do. Now, when I usually do so, I hardly pause (except for breath), and I only rarely make mistakes. If I do, I correct them immediately, and continue reciting the digits. However, this time, I only recalled the first ten: 3.1415926535... before pausing, continuing with some random sequence of numbers which I immediately knew was wrong and tried to correct myself, got it wrong again, and had to break off. I restarted the recital, but couldn't get to even 20 decimal places. Something was terribly wrong, or I was terribly rusty. When I woke up, I recited it just to be sure. As it turns out, I got it almost flawless, and without halting too. Clearly, there was something different about the dreamstate.
It's now been almost 4 years since I memorised the 140+ digits of Pi. I don't need to revise it on a regular basis, unless I want to make a completely flawless and smooth recital. It, as some might put it, is practically ingrained in my memory. Yet, while in the dreamstate, I had immense trouble recalling, and also couldn't go past the front. I wasn't lucid, so the only conclusion that I can come up with, is that (since I wasn't lucid, hence only the subconscious was actively functioning, while the conscious was just lumbering around,) for perfect memory recall, the conscious needs to be active and functioning.
Habits seem to be easily stored in the subconscious, as so are memories, and seem to be easily called into play in dreams (whether lucid or not). You can easily walk, talk, and interact with your environment and "be yourself" while not being lucid. So, it looks like the subconscious holds an important part of your mental functions. Yet, without the conscious, something more difficult and complex like the 140+ digits of Pi couldn't be recalled. I suppose the brain has a somewhat RAID 0 like partition which these memories are stored. Striped half into conscious sector, and half into subconscious. Data cannot be retrieved in its entirety if either partition is unreadable or dysfunctional.
The conscious mind apparently plays a part in some of our memory recall/storage. More remains to be explored...