6. What is the purpose of dreaming? (proposed — Bill) discussed 29 June 2013
What is the purpose of dreaming? (i.e. what evolutionary advantage would a dreaming creature have over one that does not dream?) There are many existing theories, such as emotional reboot, building neural networks for visual processing, etc., but there is no genuine consensus on the issue.
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Comments on Dreaming
Thor May
29 June 2013
1. People tend to see what they want to see and hear what they want to hear. This stabilizes their identity and self-confidence. Phenomena that are separated from direct sensory input are even more liable to this process. Hence faith based religion, and ergo, the interpretations of dreaming. Therefore we are unlikely to change anyone’s mind during this discussion about their favourite dreaming theories!
2. In every culture, there is an enormous accumulation of stories, beliefs and habits of interpretation attached to dreaming. This stuff is a rich anthropological source for understanding patterns of human behaviour. It does not necessarily give insight into a scientific understanding of dreaming.
3. Dreaming can occur during various sleep stages, but is most common and intense during REM sleep. REM sleep occupies about 25% of sleep time, and the length of dreams increases from about 10 minutes to about 20 minutes at the end of the night.
4. Many animals sleep. Apparently armadillos are amongst the biggest dreamers. The evidence for such dreaming comes from brain imaging. It would seem then that IQ is no qualification for dreaming.
5. Long term declarative (not procedural) memory storage is known to depend upon processing by the hippocampus during sleep. Sleep deprived subjects have severely impaired memory. The relationship between dreaming and this kind of mental housekeeping is unknown, except that the the neurotransmitters, norepinphrine, serotonin and histamine are blocked during REM sleep, while the stress neurochemical, cortisol often increases in late REM sleep, and interferes with the conversion of short term memory to long term memory (thus 95% of dreams are forgotten).
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6. The following is my own, completely unsupported guess at what dreaming may be about:
a) Our entire reality or self-identity is a mental construct of habits + memories + incoming external sensation.
b) This mental construct is not a solid thing. It is a finely balanced, self-correcting web of organized relationships. That organization is both chemical and electrical. The organization, I think, probably has a lot to do with the mathematical behaviour of complexity itself, which tends to generate order from disorder.
c) My guess is that the self-correcting nature of self-identity depends upon the constant input of external sensation. During sleep the input of external sensation, especially visual and balance signals, is dramatically reduced. In a way this “frees the mind” to wander and to play with unusual combinations.
d) The amount of mental wandering in dreams varies a great deal, both between people (if we are to believe reports) and within individual experience.
e) My hypothesis (again unsupported) is that the mental wandering within dream periods assists the maintenance of the “reality illusion” in a waking state by exploring alternative possible realities, minus the discipline of direct sensation. Awareness and rejection of these alternatives by our daytime “reality illusion” (our identity) may be compared to setting navigation beacons for safe channels in a tidal river. If this is so, then dreaming would have clear evolutionary value for survival.
7. Allowing our minds to wander is not restricted to dreaming. Absent-minded behaviour, day dreaming, drug induced deviations are further examples. It is a matter of degree. The “half-sleep” state prior to full sleep or full waking seems to be another example of identity which is partly without the discipline of external sensation or conscious purpose. For example, my 90 year old mother tells me that she regularly wakes now with the feeling that one of her sisters is in the bed and mustn’t be disturbed. Eighty years ago her five sisters regularly had to share beds.
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thormay@yahoo.com
http://thormay.net
summary of dream theories: http://en.wikipedia.org/wiki/Dream