Thanks to everyone who tried to answer my question about how you sometimes know that your dream is a dream. I offer a selection from the answers.
Natalie says: 'you know because you are coming out of the dream'. Read the rest of what she says, which suggests that Natalie is an extremely well-organized dreamer. One reader concurs with this, saying we know we're dreaming at 'the point when we are about to leave the unconscious sleep phase, and enter into consciousness'. Another writes that I'm 'describing "lucid dreaming", during which one retains an awareness that one is dreaming'.
More technically and in more detail (and if you get lost anywhere in this, just skip ahead to where you'll find things a bit more manageable again, and indeed remarkable):
I suspect the answer to your question will be found in the increasingly persuasive evidence that we're rarely, if ever, entirely awake or asleep - just in various stages and states of consciousness. 'Synchrony between single neurons in humans during sleep' (Kreiman et al) explains this continuum of self-awareness, at least as it applies to various unconscious states, pretty straightforwardly:For a more phenomenological approach:The period of sleep was long associated with complete cortical inhibition and brain inactivity. However, electroencephalographic (EEG) scalp recordings in humans during sleep have identified different states characterized by distinct amplitudes and frequencies. These states include slow wave sleep (SWS) where slow-varying large amplitude signals are prominent and rapid-eye-movement (REM) sleep in which the EEG signature is indistinguishable from that in the wake state. These states are repeated in a cyclical pattern during sleep.'Identifying neural correlates of consciousness: the state space approach' (Juergen Fell) specifically references 'waking dream' experiences:Phenomenal awareness seems not always to be absent during classically defined slow-wave sleep. In about 50% of laboratory awakenings from slow wave sleep some sort of subjective experience is reported. These so-called sleep mentations may for instance comprise imagery, thinking, reflecting, bodily feelings and fragmentary impressions.Finally, the abstract of a paper concerning the 'consolidation of memory' during sleep (which I can't find the link to at the moment) notes that Gyorgy Buzsaki's......electrophysiological model of a hippocampal-neocortical dialogue during sleep posits a transfer of data from neocortex to hippocampus in active waking, and consolidation of information within the hippocampus along with its transfer back to the neocortex for longer-term storage during quiet waking and NREM. Recent experimental and theoretical work further indicates that intracortical processing occurs during REM, at which time new associative connections might be formed within the neocortex.Such interactions between the 'seat of consciousness' neocortex and the 'RAM drive' hippocampus indicate that a wide variety of neurological debates take place around the table of our nodding heads. It shouldn't be too surprising, then, that when it's our canny neocortex's turn to speak, our dreaming selves occasionally suspect that the conversation, despite its vividness, might not be entirely 'real'. At least I think that's why we sometimes notice we're dreaming but usually don't.
I don't know the 'why' of being able to know you're dreaming, either, but I know exactly what you're talking about. When I was a child I used to get out of bad dreams by intentionally throwing myself off cliffs, having heard somewhere while awake that if you fall in a dream you will wake up because obviously you can't hit the bottom - that would mean you'd get hurt, which can't happen in a dream. I consciously put it to use and it worked, which still blows my mind. And just the other night I found myself in a dream I didn't like, knew it was a dream, and wrenched myself awake (without using a cliff). I guess a neurologist or a neuropsychologist might have some ideas, but I'm certainly at a loss.Sounds better than intentionally throwing oneself off cliffs. And a reader from Minnesota offers an interpretation of the particular dream I reported:
What's really cool in dreams is flying. My flying is not like the easy soaring of an eagle; it takes some effort and I'm usually only twenty or thirty feet above the ground. But it's great anyway.
[A] phone many times in a dream symbolizes communication with others, usually a close friend or loved one. The phone lost, missing, or stolen can symbolize a fear or a deep seated unconscious anxiety over not being able to communicate. My guess (and I would freely admit it may not be right) is that with the pressure of thousands of daily readers the world over, you have understandable anxiety over living up to their expectations. A missing phone in a dream may very well be (and again might not) an anxiety dream over that daily reality.(I must put this post up before anyone gets impatient.)