Since there's been some discussion and thought about the function of dreams, I'd like to add some. Most theories deny that the conscious experience of dreaming itself would be useful in a biological sense, it's only the neurophysiologcal events associated with dreaming that are useful in this sense.
Activation synthesis theory (and AIM being a sort of update to it) treat dreams and mere byproducts of neurological events, ie random noise.
Then there's the reverse learning theory, which is basically pretty similar, dreams are byproducts of the "cleaning up" process which occurs in the brain during REM sleep, this happens to clear up memory space to avoid "overload".
Then we have Flanagan who denies that dreaming would be functional at all.
There's a cognitive theory of dreaming also, according to it, dreams are formed by diffuse mnemonic activation, ie. different memory traces are in a random/semi-random manner. Then a "dream production system" organizes these activated traces into coherent experiences, this system draws upon knowledge of how events are ordered in the waking world and builds scripts from that information.
So the phenomenal part of dreams seems to widely regarded as an epiphenomenon, but there's of course the idea of dreams as a problem/emotional solving facility.
Finally we have some theories that take dreaming to be functional in the evolutionary sense.
One regards sleep as an adaptive mode of behaviour for creatures that had to spend most of their time hiding. The REM sleep period then serves a preparatory function, it actives the brain in order to prepare it for possible fight/flight. So it works as some kind of anticipatory system to help out in events encounterd immediately after havig had a dream.
Yet another theory proposes that information important for survival is accessed during REM sleep and then integrated with past experience to provide a strategy for future behaviour (hippocampal thetha rythms during wakefulness and REM sleep, these rythms haven't been recorded in humans though).
Last in this little list is the threat simulation theory of dreaming, which is the most recent. It says that: "The biological function of dreaming is the simulation of threatening events and the repeated rehersal of threat perception and threat avoidance responses"
So dreming is an evolutionary adaptation, it's function is threat simulation and the function evolved as a repsonse to ancestral selection pressures.
It works by a dream production mechanism selecting memory traces from long term memory which are then used as a base for constructing dream images. Memories with the highest emotional salience and/or most recently encoded/re-activated are most likely to be selected, these memories often include information about situations critical to survival.
Hence threatening waking events will be simulated repeatedly in various combinations in dreams, if this develops/maintains threat avoidance skills, it would have increased the fitness of the individuals in posession of it, ie. higher survival/reproduction rate.
The theory also included six empirically testable propositions, but I'm too lazy to write more on this subject.
When it comes to lucid dreaming it would be nice to get some test subjects with a stable recurrence of lucid dreams together, then do a functional brain scan of them as they enter the lucid dreaming mode. Since you supposedly need an active prefrontal cortex to have anything more than basic phenonmenal consciousness, the hypothesis would be frontal lobe activity correlated with the lucid dreaming, if that didn't happen, it would pose some interesting questions. Can't understand why noone has done the experiment already
On a more personal note, lucid dreaming in fun when you are fully in control, which doesn't always happen. As mentioned by some other people earlier an easy induction technique is to keep track of things that you find impossible to do when dreaming (like reading, using some technical devices and such), then try to do those things, which should help increase your rate of lucid dreams a bit, without much effort.
Hi All.
My concern is that many folks I've talked with tend to attach some kind of religious or spiritual significance to lucid dreaming. This bothers me because I'd rather have a discussion with other LD'ers that is stripped of "enlightenment" overtones. A lot of the boards on the net tend to group LDs with out-of-body experiences and TM, which in my opinion is pure quackery. LD'ing is nothing more than simply realizing when you're dreaming, that's it. There's no mystery/magic about it.
As a reply to this, I'm not sure what TM is, but I wonder why you talk about OBEs as pure quackery? In the sense of there being some silly kind of astral body, I obviously agree with you, but if you are trying to deny experiences that doesn't seem like a smart thing to do. Various forms of autoscopic phenomena (AP/OBE is about the same thing, just that in AP, you by definition see yourself or some form/shadow of yourself) have been researched and there is nothing quacky about it.
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I just checked and I guess TM stands for Transcendental Meditation, which I don't know much about, but just like when it comes to other forms of meditation, there's been studies and meditation has been correlated with increased gamma activity and supposeedly increased alpha/gamma/theta activity in TM.
If you are merely pointing to the fact that it would be quackery for TM practitioners to point to some "other-wordly" effect of TM, I agree. Fringe phenomena in themselves, their phenomenological aspects and neural correlates are highly interesting though and in my opinion a necessary part in the scientific study of consciousness, just like you can infer disociations from cases in neuropsychology.
Anyway, rant mode off...
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), and informational experience. I am provided with what I call "Dream Knowledge" which I can only describe as "That which is known to be true in the dream reality." Even if I'm semi/fully lucid there tends to be information that I have regarding the situation that I can usually understand to have only originated from the dream.