16.1: Chapter 1

4.1.1. Listening Comprehension

00:06 In the third millennium BCE,

00:08 Mesopotamian kings recorded and interpreted their dreams on wax tablets.

00:13 A thousand years later,

00:15 Ancient Egyptians wrote a dream book

00:17 listing over a hundred common dreams and their meanings.

00:20 And in the years since,

00:21 we haven't paused in our quest to understand why we dream.

00:25 So, after a great deal of scientific research,

00:28 technological advancement,

00:29 and persistence,

00:31 we still don't have any definite answers, but we have some interesting theories.

00:36 We dream to fulfill our wishes.

00:40 In the early 1900s,

00:42 Sigmund Freud proposed that while all of our dreams, including our nightmares,

00:46 are a collection of images from our daily conscious lives,

00:49 they also have symbolic meanings,

00:51 which relate to the fulfillment of our subconscious wishes.

00:55 Freud theorized that everything we remember when we wake up from a dream

00:59 is a symbolic representation

01:01 of our unconscious primitive thoughts, urges, and desires.

01:05 Freud believed that by analyzing those remembered elements,

01:08 the unconscious content would be revealed to our conscious mind,

01:12 and psychological issues stemming from its repression

01:14 could be addressed and resolved.

01:17 We dream to remember.

01:20 To increase performance on certain mental tasks,

01:23 sleep is good,

01:24 but dreaming while sleeping is better.

01:27 In 2010, researchers found

01:28 that subjects were much better at getting through a complex 3-D maze

01:32 if they had napped and dreamed of the maze prior to their second attempt.

01:37 In fact, they were up to ten times better at it

01:39 than those who only thought of the maze while awake between attempts,

01:44 and those who napped but did not dream about the maze.

01:48 Researchers theorize that certain memory processes

01:51 can happen only when we are asleep,

01:53 and our dreams are a signal that these processes are taking place.

01:58 We dream to forget.

02:02 There are about 10,000 trillion neural connections

02:05 within the architecture of your brain.

02:07 They are created by everything you think and everything you do.

02:11 A 1983 neurobiological theory of dreaming, called reverse learning,

02:15 holds that while sleeping, and mainly during REM sleep cycles,

02:19 your neocortex reviews these neural connections

02:22 and dumps the unnecessary ones.

02:25 Without this unlearning process,

02:27 which results in your dreams,

02:28 your brain could be overrun by useless connections

02:31 and parasitic thoughts could disrupt the necessary thinking

02:34 you need to do while you're awake.

02:37 We dream to keep our brains working.

02:42 The continual activation theory proposes that your dreams result

02:46 from your brain's need to constantly consolidate and create long-term memories

02:51 in order to function properly.

02:53 So when external input falls below a certain level,

02:55 like when you're asleep,

02:57 your brain automatically triggers

02:58 the generation of data from its memory storages,

03:01 which appear to you in the form of the thoughts and feelings

03:04 you experience in your dreams.

03:06 In other words,

03:07 your dreams might be a random screen saver your brain turns on

03:10 so it doesn't completely shut down.

03:14 We dream to rehearse.

03:18 Dreams involving dangerous and threatening situations are very common,

03:21 and the primitive instinct rehearsal theory

03:24 holds that the content of a dream is significant to its purpose.

03:27 Whether it's an anxiety-filled night of being chased through the woods by a bear

03:31 or fighting off a ninja in a dark alley,

03:34 these dreams allow you to practice your fight or flight instincts

03:37 and keep them sharp and dependable in case you'll need them in real life.

03:41 But it doesn't always have to be unpleasant.

03:43 For instance, dreams about your attractive neighbor

03:46 could actually give your reproductive instinct some practice, too.

03:50 We dream to heal.

03:54 Stress neurotransmitters in the brain are much less active

03:57 during the REM stage of sleep,

03:59 even during dreams of traumatic experiences,

04:02 leading some researchers to theorize

04:04 that one purpose of dreaming is to take the edge off painful experiences

04:08 to allow for psychological healing.

04:10 Reviewing traumatic events in your dreams with less mental stress

04:13 may grant you a clearer perspective

04:16 and enhanced ability to process them in psychologically healthy ways.

04:20 People with certain mood disorders and PTSD often have difficulty sleeping,

04:25 leading some scientists to believe that lack of dreaming

04:28 may be a contributing factor to their illnesses.

04:32 We dream to solve problems.

04:37 Unconstrained by reality and the rules of conventional logic,

04:40 in your dreams, your mind can create limitless scenarios

04:43 to help you grasp problems

04:45 and formulate solutions that you may not consider while awake.

04:49 John Steinbeck called it the committee of sleep,

04:51 and research has demonstrated

04:53 the effectiveness of dreaming on problem solving.

04:56 It's also how renowned chemist August Kekule

04:58 discovered the structure of the benzene molecule,

05:01 and it's the reason that sometimes the best solution for a problem

05:05 is to sleep on it.

05:06 And those are just a few of the more prominent theories.

05:10 As technology increases our capability for understanding the brain,

05:13 it's possible that one day

05:15 we will discover the definitive reason for them.

05:18 But until that time arrives, we'll just have to keep on dreaming.

“Why Do We Dream?” by Amy Adkins is licensed by TED under CC BY-NC-ND 4.0