It’s possible I have an answer to that particular question…not necessarily the only answer, but one I can at least document.

I used to dream constantly my teeth were rotting, turning to mush, or for other reasons falling out…sometimes a single tooth, sometimes all of them.

About 7 years ago, I switched dentists based on a friend’s enthusiastic recommendation. At my first visit, the new dentist noted, among other things, it appeared I had been grinding my teeth frequently. I said I was unaware of it; she replied tooth grinding tended to occur most often during sleep, and unless one’s partner or spouse commented on it, most people remained unaware of it, unless they were familiar with the related symptoms.

She also said a problem with one’s bite was the most usual cause, and went through a common procedure for correcting the problem, i.e., identifying the problem spots using a sort of dental “carbon paper” on which I bit down, then gently grinding down any colored hot spots until no more could be found.

I mentioned this to my partner, who confirmed I often ground my teeth while sleeping. (I omit the brief, mostly amicable, discussion which ensued as to why he had not shared that observation with me previously.)

After a second bite correction a month later, I stopped grinding my teeth at night.

Since then, I haven’t had a single dream in which my teeth – or even a single tooth – rotted, turned to mush, or fell out.

I’m not claiming other people’s tooth-loss dreams invariably incorporate the same “warning” or occur for the identical reason. I only wanted to document my experience, since my own tooth-loss dreams were definitely resulting from night-time tooth-grinding.

If anyone questions that conclusion, I would be interested in hearing their reasons for doing so, so long as their reasons and arguments are logical and have some documented basis in fact. I’d especially also be interested in any scientific studies or publications including similar instances.

For what it’s worth.

All best,
cordwainer

But I think you nailed it with the statement: “However, the dreaming brain does not appear to be responding to the sensory data that flows from true physical experience. This leads us to question exact what is the dreaming brain perceiving, interpreting and answering.” Indeed! That’s where dream research begin to get interesting.

Lastly, have you seen Tore Nielen’s recent work about the hippocampus and the neocortex switch hitting with activity during the memory consolidation process? He’s got some interesting data correlated with day residue and memory incorporations from dream reports.

In the normal brain, dreaming appears to initiate at the onset of atonia. Atonia, as Sir Charles Sherrington discovered and Dr. Michel Jouvet later confirmed, is mediated by neural activity in the metencephalic region of the brainstem. Spinal cord aside, the brainstem is the most primitive component of our central nervous system (CNS) and the evolutional evidence I???ve studied suggests that atonia evolved as an effective means to extend resting animals??? tolerance of prolonged periods without the availability of life sustaining nutrients. In preexistent animals, as in contemporary species, atonia results in the suspension of muscle tone (muscle readiness) and the devotion of energy reserves to neurological and biological systems more vital to survival. At the onset of atonia in contemporary animals, increased heart, lung and brain activity results in more energy usage by these organs.

If we accept the preexistence of animals with metencephalic neural functions (inclusive of atonia) before those with the neural activity and grey matter structures associated with the contemporary dreaming brain, then the activity in the brainstem (atonia) that is perceived as the initiate of dreaming in contemporary animals paints an evolutional portrait of dreaming as an ???after-effect??? of what began as a neural function to sustain life through privation periods.

As to the question of dreaming???s value, I cannot find a single studied that suggests the benefits of dreaming without atonia; however, atonia without dreaming appears to offer benefits equal to normal dream sleep. Rather than dreaming, the evidence appears to promote the value of atonia to beneficial sleep. So the question remains: what is the function of dreaming?

The uptake of energy by the primitive neural components of the contemporary brain at the onset of atonia stimulates neural activity, which activates brain function to almost wakeful levels. The distinction between this type of wakefulness (dreaming) and true wakefulness (consciousness) is the partial cessation of somatosensory afference: the dreaming brain???s connection to physical sensory and reality is partially severed.

When we dream, physical sensory data does not enter our wakeful brain activity as it does when we are consciously awake. Without this data, the dreaming brain???s ability to distinguish physical experience and reality is impaired. When we awake from a dream, we are able to distinguish our experiences within as a dream from true physical reality because of the physical sensory data that rushes into our conscious brain from its reactivated and tonic physical sensory array. Whether we are dreaming or consciously awake, there is no evidence suggesting that our brain engages in a function that is distinct from what it was evolved to do.

I think most researchers agree that the evolved function of our brain is to perceive, interpret and response to sensory data. However, the dreaming brain does not appear to be responding to the sensory data that flows from true physical experience. This leads us to question exact what is the dreaming brain perceiving, interpreting and answering.

The decorticate experiments performed by Jouvet and other researchers showed that the cortex does not engage in any activation without a neural link to subcortical structure. This suggests that the dreaming brain may only engage in this activity through the activation or sensory input from subcortical structure. Simply, the dreaming brain appears to be perceiving, interpreting and responding to sensory data generated by brainstem activation in the absence of a connection to true physical inexperience. Specifically, it is my opinion that the dreaming brain is responding to influences that initiate through hypothalamic activation. This appears to place the source of dream content outside those associated with stored memories.

Looking at the evidence brain evolution appears to provide, I???ve formed very firm opinions about the nature of the mind as it might relate to dreaming and consciousness. From the perspective of brain evolution I???ve studied, a mind is the environment of cognitive activity within the brain that arises from brain function. Neurologically, a mind is quantified by the structure in the brain that gives it???s host the capacity to integrate divergence types of sensory data (aural, tactile, visual, olfactory, oral) in a way that allows the host to engage in behaviors independent of instinct. This is the ability to behave proactively rather than reactively. In the human brain, the structure that appears to give us this ability is the thalamus, which happens to be a brainstem structure of striking resemblance to cortical structure with a right and left hemisphere and hemispheric adhesion.

But I doubt Revonsou would share my opinion. His assumption is that threat simulation pushes back into early mammalian cognition, but he does not actually posit a biological strata or mechanism for such a cognitive leap. This discussion highlights how important it is for some to find biological functions for dreams, in a way so dreaming can be blessed by the white coats of science, today’s shaman-priests and holders of knowledge. Dreaming is looking for legitimization by the sciences and so it often adopts its language – much like anthropology as a field of study, and psychology as well. There was a time, a hundred years ago, that biology sought this legitimization from the ivory tower as well.

The secret moral dilemma underneath this struggle is this question: Is dreaming simply a psychological “after-effect” of a deep biological process – and therefore, is it really valuable? This is a mirror of the larger debate in consciousness studies: is consciousness a thing in itself, or is it an epi-phenomenon?

According to my study of the available research, dreaming began at the diencephalic stage of brain evolution. Interestingly, the muscle immobility (atonia) that accompany dream sleep evolved in the brain millions of years before it began to dream. The desynchronous brain activity associated with consciousness and dreaming evolved as the brain became capable of processing visual sensory.

The contemporary brain begins to dream at the onset of atonia. My study suggests that atonia evolved as a means to extend the energy reserves of resting animals through periods or cycles of food privation. This process allowed these primitive animals to devote more of their energy reserves to physiological systems more vital to their survival such as heart, lung, and brain.

Resting animals had no need for muscle toncity or readiness during extend periods of food privation. However, they did have need to remain alert to the restoration of food sources.

Dreaming, as my study suggests, is a consequence of the sensory vigilance primitive animals required to remain alert to restored food sources. These early animals didn’t actually dream; they just had actively alert brains of the kind that gave rise to the dreaming brain. This is suggested in contemporary animals through functional study of decortication. Functional study of the normal dreaming brain suggests that dreaming is a type of consciousness or wakefulness rather than sleep.

Evolution of the brain suggests even more about why we remain mostly immobile while our eyes move rapidly when we dream. Our eyes move because their muscle evolved in the brain after those that control muscle tone in the body; our eye evolve with the dreaming dreaming. There is even more to be said as to why dreams are difficult to remember without practice. Evolution of the brain, my friend, is the key.

so, Kris: I think Valli and Revonsuo would respond by suggesting that many of today’s threats are not the ones we’ve been “hardwired” for in the last few hundred thousand years – on the other hand, the classroom dream is a form of social stress/embarrassment and that’s variable but definitely old-school. I spoke to Valli about this point and she suggested that basically “the modern era is not adaptive” ie. there are many novel threats that may not trigger threat simulation or vice versa, insignificant threats may trigger the simulation.

dreams of teeth: now that’s old-school! They are literally the greatest source of our mortality and definitely constitute a threat/indicator of health. Modern dentistry has shielded most of the first world from that ugly truth, but in the old days, and in many parts of the world today, an infected abscessed tooth can be deadly. (side note: out teeth were healthier before we adopted the grain diet of the neolithic, 6000 years ago).

so, based on their research, if you live a tough life (early exposure to trauma, personal or systematic), there are more likely to be perceivable threats in the dream. I suppose it’s preparation for the future but also a healing process, if we look to clinical psychology to deepen the theory.

Kathleen – thanks for the compliment and I think you’re on to something that the theory does not address: bizarre (non-rational) responses to dream threats. I melt through walls myself. My attention turns towards the emotional valence in these situations, not the concrete imagery – in other words, gaining courage in traumatic dreams may be helpful for preparing for everyday life’s surprises.

And I’m not sure of Revonsuo’s take on animal dreams (animals dreaming dreams, i mean). Most cognitive researchers are comfortable with dreaming as a proto-mammalian thing at least, given the presence of REM in lower mammals.

of course, dreams do not equal REM. but that’s what we’ve got on the material strata.

Kevin: you’re right about REM deprivation; it’ll mess you up bad, and can lead to native hallucinations (also called REM intrusion) and put you in bodily harm. Eventually you just go to sleep no matter what the stimulus is, iow you pass out cold. There is currently no complete scientific theory that accounts for the need for sleep from a biological perspective. Memory consolidation seems to be the best bet for consciousness-related topics, but all kinds of complex cellular refreshments happen too during sleep.

I agree with you about consciousness and dreams: it’s hand in hand. It’s impossible to discuss the significance of dreaming without nodding to the need to make meaning from these experiences.