Domhoff’s Perspective
Before offering my list of potential functions, I should note that William Domhoff, one of the long-time leaders in the study or sleep and dreaming, believes that dreams serve NO adaptive functions. In The Emergence of Dreaming (Domhoff, 2017) provides research findings to support his negative appraisal regarding the evolutionary importance of dreaming.
According to Domhoff, dreaming is similar to the wandering of our mind during the day. He buttresses his argument by noting that the neurocognitive base for dreaming is also that for our mind-wandering activities. He believes that dreams are a biological accidence—the kind of process that accompanies something that is of value (in this case certain cognitive abilities and neurobiological processes that are engaged when we are awake and learning how to survive in a world that is often hostile. Perhaps it is similar to the human habit of defining the in-group and out-group that might be a very non-adaptive spin-off from the highly adaptive tendency of humans to nurture and bond with those closest them (members of their own family and tribe).
Domhoff (2017) does consider dreams to be indirectly valuable (and perhaps adaptive) in that they often play a central role in the healing practices and spiritual ceremonies to be found in many societies. Perhaps this is where dreams hitch on to the adaptive role I just mentioned of human nurturing and bonding. Thus, it might be that dreams do serve several important functions – even if it is only after we wake up, process and begin to use the dream content in our personal and collective lives. I will keep this in mind when offering my own list of functions.
Walker’s Perspective
I do need to introduce one other more contemporary perspective on dreams. It is offered by Matthew Walker (2017). Like Domhoff, Walker is a member of the pantheon of noted researcher on sleep and dreaming (though a more recently joining member). Walker (1917, pp. 206-207) has this to say about evolution, REM sleep and dreaming:
. . . evolution may have gone to great lengths to construct the neural circuits in the brain that produce REM sleep and the functions that REM sleep supports. However, when the (human) brain produces REM sleep in this specific way, it may also produce this thing we call dreaming. Dreams . . . may serve no function. Dreams may simply be epiphenomena of no use or consequence. They are merely an unintended by-product of REM sleep. . . .If . . ,. You need both REM sleep and to be dreaming about specific things to accomplish [important] functions, it would suggest that REM sleep alone, although necessary, is not sufficient. Rather, a unique combination of REM sleep plus dreaming and dreaming of very particular experiences, is needed to transact these nighttime benefits.
To cut to the chase, Walker (2017, p. 205) seems to disagree with Domhoff about the functionality of dreams. He asks: “do dreams themselves, above and beyond REM sleep, actually do anything for us?” Walker answers his own question: “As matter of scientific fact, yes, they do.” Specifically, he identifies two major benefits that have been shown to accrue when REM and dreaming are engaged (+-Walker, 2017, p. 207). These relate to “nourishing our emotional and mental health” and assisting “problem solving and creativity.” I bring both of these benefits to the fore when considering the diverse functions served by dreaming.
