To sleep, perchance to dream


Why do we dream?

You’d think we’d know by now. Everyone dreams, and people have been fascinated by dreams throughout recorded history. But scientifically, their origin and importance remain uncertain. Do they serve some vital psychological or physiological function? Or are they just meaningless accidents of our brain’s wiring?

A few years ago, Finnish psychologist Antti Revonsuo theorized that dreams evolved as a way to rehearse threatening situations.

Silvio Scarone of the Universita degli Studi de Milano in Milan, Italy, explains it this way: “The environment in which the human brain evolved included frequent dangerous events that posed threats to human reproduction. These would have been a serious selection pressure on ancestral human populations and would have fully activated the threat simulation mechanisms.”

For most of the time humans have been evolving, the most common threatening situation was a wild animal attack, and it’s interesting to note that children, often viewed as being closer to their evolutionary ancestors than grown-ups, dream particularly often of animal or monster attacks.

Another bit of evidence is the fact that people who suffer from REM Sleep Behavior Disorder (RBD), who lack the mechanism that normally immobilizes the body during the dreaming stages of sleep, often act out violently: patients flail, kick and punch in their sleep; kick holes in walls; try to jump out windows or set fire to things, or even try to choke those sleeping with them—and often report they were dreaming of fending off attackers, protecting their families, or fleeing a threat.

A 2005 study of 98 patients with RBD showed that they reported having violent dreams more than four times as often as healthy people. In other words, their “threat-simulation system” seems to be hyperactive.

But threat simulation doesn’t completely explain dreaming, which after all isn’t completely focused on threatening situations. Dreams also seem to have a role in the learning process, helping you integrate information your brain absorbed while you were awake. You can often remember things better the day after you learned them than you could at first…which is why “Let’s sleep on it” is valuable advice before making decisions of any sort.

It’s hard to pin down the psychological reasons for dreaming because you can read just about anything you want into dreams (which is why interpreting them has been such a profitable occupation for charlatans for most of human history). Studies show that people attribute more meaning to dreams when it corresponds with their pre-existing beliefs and desires.

So, people consider pleasant dreams about people they like more significant than pleasant dreams about people they dislike, and vice versa—that is, they ascribe more significance to unpleasant dreams about people they dislike than unpleasant dreams about people they like.

Similarly, people who believe in God are more likely to consider any dream in which God speaks to them as meaningful than agnostics, who tend to consider dreams in which God speaks to them more meaningful when God commands them to take a pleasant vacation than when He commands them to engage in self-sacrifice.

In other words, dreams feel meaningful, but the meaning is one we impose based on our waking personalities rather than anything arising from the dreams themselves.

Now a Harvard psychiatrist and sleep researcher says that while there may be psychological value to dreams, their more important function may be physiological.

Dr. J. Allan Hobson holds that during REM sleep the brain is essentially just “warming its circuits” by anticipating the sights, sounds and emotions of the waking state. The metaphor he uses is jogging: just as the body does not remember every step of a jog, but knows it has exercised, so we don’t remember many of our dreams, but our brain has nevertheless been exercised so that it’s ready for the rigors of waking life once more.

In this view, dreams represent a parallel state of consciousness that’s always running, but which is suppressed while we’re awake. When both states of consciousness are in play at once, Hobson says, we get lucid dreaming, the ability to watch a dream as an observer without waking up.

The arguments and research will no doubt continue indefinitely…as, too, will the dreams.

Sleep tight!

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