How Does Science Interpret Dreams?

From Joseph’s interpretations of Pharaoh’s dreams to Freud’s analyses of dreams as repressed unconscious urges, to our casual readings of dreams of falling, being chased, losing teeth, and feeling unprepared for class, we seek meaning in the narratives and images that emerge during sleep.  Modern sleep science provides a framework for understanding why we dream.

Dreams occur in all depths and types of sleep.  They are, however, most concentrated in rapid eye movement, or REM, sleep.  REM sleep is defined by the presence of these rapid eye movements, skeletal muscle paralysis, and rapidly oscillating brainwaves.  Rapidly oscillating brainwaves require high levels of energy to generate.   Other stages of sleep require less neuronal energy than REM sleep and help the brain recover.  Why have we evolved a stage of sleep that uses so much energy?  Also, muscle paralysis allows us to dream without acting out our dreams.  Paralysis clearly carries a great risk- imagine if a prehistoric lion attacked paralyzed prehistoric you.  Evolution accepts risks only when rewards are proportional.

The value of dreams may relate to their role in cognition.  First, there is an evolving scientific consensus that dreams foster learning.  If I gave you a difficult puzzle now, you might not be able to solve it.  If I asked you to come back in later on today, you still might not have the solution.  But if I asked you to come back after sleeping tonight, you might have the answer.   If you learned and practiced a skiing video game, you’d get better with practice- up to a point.  If you came back later, you’d not have made much progress since your first set of trials.  If you come back tomorrow after sleeping, you’ll likely perform better, and the more you dreamt about skiing, the more improvement we would see.   Some scientists have hypothesized that dreams play out potential scenarios to improve our performance in those scenarios; such a hypothesis helps explain why so many of our dreams involve anxiety.  Dreams may reflect your brain trying to predict the future- most of us have enough dreams and enough experiences that every so often, we have some experience that reminds us of our dreams. 

While dreams reflect the processing of experience, they do not reflect our failings.  Portions of our brain- especially those involved in decision-making- are suppressed during dreams.  We make decisions in dreams that we would not make in reality.  Activities you perform in dreams should not be a source of guilt; a dream about an activity does not mean that you wish to perform that activity.  If you have a good dream, enjoy it; if you have a bad dream, remember that it was just a dream.

For more information about dreams, consider this entertaining video or this review.  You can access more recent reviews with journal-specific subscriptions.