Why do we dream? - Amy Adkins

8,642,736 views ・ 2015-12-10

TED-Ed


Please double-click on the English subtitles below to play the video.

00:06
In the third millenium BCE,
0
6643
1769
00:08
Mesopotamian kings recorded and interpreted their dreams on wax tablets.
1
8412
5394
00:13
A thousand years later,
2
13806
1340
00:15
Ancient Egyptians wrote a dream book
3
15146
2102
00:17
listing over a hundred common dreams and their meanings.
4
17248
3406
00:20
And in the years since,
5
20654
1209
00:21
we haven't paused in our quest to understand why we dream.
6
21863
3787
00:25
So, after a great deal of scientific research,
7
25650
2471
00:28
technological advancement,
8
28121
1666
00:29
and persistence,
9
29787
1218
00:31
we still don't have any definite answers, but we have some interesting theories.
10
31005
5438
00:36
We dream to fulfill our wishes.
11
36443
4494
00:40
In the early 1900s,
12
40937
1557
00:42
Sigmund Freud proposed that while all of our dreams, including our nightmares,
13
42494
4018
00:46
are a collection of images from our daily conscious lives,
14
46512
3339
00:49
they also have symbolic meanings,
15
49851
2050
00:51
which relate to the fulfillment of our subconscious wishes.
16
51901
3563
00:55
Freud theorized that everything we remember when we wake up from a dream
17
55464
3690
00:59
is a symbolic representation
18
59154
1896
01:01
of our unconscious primitive thoughts, urges, and desires.
19
61050
4485
01:05
Freud believed that by analyzing those remembered elements,
20
65535
2954
01:08
the unconscious content would be revealed to our conscious mind,
21
68489
3693
01:12
and psychological issues stemming from its repression
22
72182
2565
01:14
could be addressed and resolved.
23
74747
2868
01:17
We dream to remember.
24
77615
3174
01:20
To increase performance on certain mental tasks,
25
80789
2403
01:23
sleep is good,
26
83192
1343
01:24
but dreaming while sleeping is better.
27
84535
2572
01:27
In 2010, researchers found
28
87107
1674
01:28
that subjects were much better at getting through a complex 3-D maze
29
88781
3986
01:32
if they had napped and dreamed of the maze prior to their second attempt.
30
92767
4709
01:37
In fact, they were up to ten times better at it
31
97476
2497
01:39
than those who only thought of the maze while awake between attempts,
32
99973
4238
01:44
and those who napped but did not dream about the maze.
33
104211
4528
01:48
Researchers theorize that certain memory processes
34
108739
2530
01:51
can happen only when we are asleep,
35
111269
2132
01:53
and our dreams are a signal that these processes are taking place.
36
113401
4801
01:58
We dream to forget.
37
118202
4342
02:02
There are about 10,000 trillion neural connections
38
122544
2509
02:05
within the architecture of your brain.
39
125053
2562
02:07
They are created by everything you think and everything you do.
40
127615
3895
02:11
A 1983 neurobiological theory of dreaming, called reverse learning,
41
131510
4359
02:15
holds that while sleeping, and mainly during REM sleep cycles,
42
135869
3621
02:19
your neocortex reviews these neural connections
43
139490
3275
02:22
and dumps the unnecessary ones.
44
142765
2564
02:25
Without this unlearning process,
45
145329
1766
02:27
which results in your dreams,
46
147095
1829
02:28
your brain could be overrun by useless connections
47
148924
2699
02:31
and parasitic thoughts could disrupt the necessary thinking
48
151623
3339
02:34
you need to do while you're awake.
49
154962
2341
02:37
We dream to keep our brains working.
50
157303
5512
02:42
The continual activation theory proposes that your dreams result
51
162815
3442
02:46
from your brain's need to constantly consolidate and create long-term memories
52
166257
5294
02:51
in order to function properly.
53
171551
1743
02:53
So when external input falls below a certain level,
54
173294
2498
02:55
like when you're asleep,
55
175792
1539
02:57
your brain automatically triggers
56
177331
1583
02:58
the generation of data from its memory storages,
57
178914
2674
03:01
which appear to you in the form of the thoughts and feelings
58
181588
2870
03:04
you experience in your dreams.
59
184458
2390
03:06
In other words,
60
186848
876
03:07
your dreams might be a random screen saver your brain turns on
61
187724
3242
03:10
so it doesn't completely shut down.
62
190966
3234
03:14
We dream to rehearse.
63
194200
3945
03:18
Dreams involving dangerous and threatening situations are very common,
64
198145
3849
03:21
and the primitive instinct rehearsal theory
65
201994
2078
03:24
holds that the content of a dream is significant to its purpose.
66
204072
3718
03:27
Whether it's an anxiety-filled night of being chased through the woods by a bear
67
207790
3860
03:31
or fighting off a ninja in a dark alley,
68
211650
2538
03:34
these dreams allow you to practice your fight or flight instincts
69
214188
3469
03:37
and keep them sharp and dependable in case you'll need them in real life.
70
217657
4063
03:41
But it doesn't always have to be unpleasant.
71
221720
2227
03:43
For instance, dreams about your attractive neighbor
72
223947
2441
03:46
could actually give your reproductive instinct some practice, too.
73
226388
4183
03:50
We dream to heal.
74
230571
3941
03:54
Stress neurotransmitters in the brain are much less active
75
234512
3274
03:57
during the REM stage of sleep,
76
237786
2053
03:59
even during dreams of traumatic experiences,
77
239839
2589
04:02
leading some researchers to theorize
78
242428
1746
04:04
that one purpose of dreaming is to take the edge off painful experiences
79
244174
4458
04:08
to allow for psychological healing.
80
248632
2249
04:10
Reviewing traumatic events in your dreams with less mental stress
81
250881
3117
04:13
may grant you a clearer perspective
82
253998
2072
04:16
and enhanced ability to process them in psychologically healthy ways.
83
256070
4070
04:20
People with certain mood disorders and PTSD often have difficulty sleeping,
84
260140
5139
04:25
leading some scientists to believe that lack of dreaming
85
265279
2920
04:28
may be a contributing factor to their illnesses.
86
268199
4490
04:32
We dream to solve problems.
87
272689
4675
04:37
Unconstrained by reality and the rules of conventional logic,
88
277364
2899
04:40
in your dreams, your mind can create limitless scenarios
89
280263
3006
04:43
to help you grasp problems
90
283269
1987
04:45
and formulate solutions that you may not consider while awake.
91
285256
4039
04:49
John Steinbeck called it the committee of sleep,
92
289295
2232
04:51
and research has demonstrated
93
291527
1497
04:53
the effectiveness of dreaming on problem solving.
94
293024
3588
04:56
It's also how renowned chemist August Kekule
95
296612
2346
04:58
discovered the structure of the benzene molecule,
96
298958
2921
05:01
and it's the reason that sometimes the best solution for a problem
97
301879
3301
05:05
is to sleep on it.
98
305180
1740
05:06
And those are just a few of the more prominent theories.
99
306920
3373
05:10
As technology increases our capability for understanding the brain,
100
310293
3563
05:13
it's possible that one day
101
313856
1641
05:15
we will discover the definitive reason for them.
102
315497
2562
05:18
But until that time arrives, we'll just have to keep on dreaming.
103
318059
3883

Original video on YouTube.com
About this website

This site will introduce you to YouTube videos that are useful for learning English. You will see English lessons taught by top-notch teachers from around the world. Double-click on the English subtitles displayed on each video page to play the video from there. The subtitles scroll in sync with the video playback. If you have any comments or requests, please contact us using this contact form.

https://forms.gle/WvT1wiN1qDtmnspy7