00:00:00
you might have figured out the reason
00:00:01
why we dream. Yes. So, it turns out if
00:00:04
you go blind, the visual cortex at the
00:00:06
back of the brain gets taken over by
00:00:08
hearing and by touch and by other
00:00:10
things, and it's no longer visual
00:00:12
cortex. We live on a planet that rotates
00:00:14
into darkness for half the time, the
00:00:17
visual cortex, the visual part of your
00:00:19
brain, is at a disadvantage. So, what I
00:00:22
realized is that the purpose of dreaming
00:00:25
is to defend the visual territory from
00:00:27
takeover from the other senses. So,
00:00:30
every 90 minutes you've got these um
00:00:33
you've got this very ancient thing in
00:00:35
your midbrain that shoots random
00:00:38
activity into the visual system, and
00:00:40
only the visual system, only this very
00:00:42
tiny part of the visual system. Every 90
00:00:43
minutes you just blast random activity
00:00:45
in here. The reason is you are just
00:00:47
defending that territory against
00:00:49
takeover. So, our colleagues at Harvard
00:00:50
did an experiment where they took
00:00:52
normally sighted people and they
00:00:54
blindfolded them tightly for 60 minutes,
00:00:56
and it turns out that 60 minutes was
00:00:58
sufficient for the visual cortex to
00:01:00
start responding to sound and to touch.
00:01:03
You could start seeing that takeover
00:01:05
happening after 60 minutes. Wow. This
00:01:08
this part of the brain really needs a
00:01:10
way of defending itself. Now, because
00:01:12
the brain is a natural storyteller, if
00:01:14
you blast random activity in there,
00:01:16
it'll, you know, put that together in
00:01:18
some sort of visual story about what's
00:01:19
happening, mostly based on what
00:01:21
connections are hot from the day, but
00:01:23
that's why we dream. So, we we dream to
00:01:27
stop the other parts of our brain
00:01:29
overtaking the visual part of our brain,
00:01:33
um overpowering it, and I guess
00:01:34
ultimately making us go blind. Yeah,
00:01:36
that's exactly right. If we lived on a
00:01:38
different kind of planet that did not
00:01:40
rotate into darkness, then we would we
00:01:43
presumably wouldn't dream. Would we even
00:01:45
need to close our eyes? I mean Not
00:01:46
necessarily. Yeah. It may be that in the
00:01:49
sleeping state, in the state of deep
00:01:50
sleep, the brain is doing particular
00:01:52
things, like taking out the trash and
00:01:54
cleaning some things up that might be
00:01:56
necessary. Who knows. But yeah, I don't
00:01:59
think we would need to dream. We
00:02:00
wouldn't need to blast random activity
00:02:01
in there,
00:02:03
um, you know, if if if our eyes were
00:02:04
always open, for example, and it was
00:02:06
always light out.
