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[Music]
we spend a huge chunk of our time
sleeping but it is not wasted time our
brains need that rest as much as our
bodies our brains can use that restful
time to subconsciously mull over
problems so today we're going to take
you on a quick tour though not through
the world of dreams but what our brains
are doing behind the curtain well that's
actually the best case scenario because
sleep doesn't always go as planned first
up if you have heard the term sleep
paralysis or experienced sleep paralysis
you may not have enjoyed it but science
generally considers it a feature of
sleep not a bug here's what happens when
our bodies don't paralyze during sleep
in the award-winning movie sleepwalk
with me based on the one man show of the
same name comedian mike berbiglia
describes the hilarious and often
startling things his body does when he
is sleeping verbiglia has rem sleep
behavior disorder or rbd a sleep
disorder that causes people to
physically act out their dreams and
while that might sound like goofy at
first think about the last dream you had
when you were running from homework
monsters or throwing punches at
voldemort maybe you wouldn't want to act
those out in real life thankfully rbd
can be treated but in some cases it also
tells a deeper story about what's
happening in someone's brain rbd affects
roughly one percent of the population
although that number is slightly higher
in older people and it's often
associated with a huge range of things
we're talking everything from
pre-existing neurodegenerative diseases
like parkinson's to narcolepsy to tumors
to certain antidepressants but
ultimately it happens because something
interferes with the brain during sleep
typically about 90 minutes after you
fall asleep you begin the rem sleep
stage rem stands for rapid eye movement
because it's when your eyes move back
and forth under your closed eyelids but
it's also the stage when you experience
most of your dreams during this time
your brain activity rises to near-waking
levels and your breathing and heart rate
speed up but typically your body isn't
able to move that's because during rem
structures in the brain stem prevent the
body from acting out dreams by relaxing
muscles and suppressing motor activity
specifically clusters of neurons from a
structure called the pons activate
neurons in another structure called the
medulla then the medulla sends signals
to motor neurons in the spinal column to
keep the muscles relaxed and put motor
activity on pause in rbd that's where
the trouble lies an issue in the palms
results in a failure to turn off those
motor neurons so someone can move as
much as they want during a dream now to
be clear a little movement during sleep
is totally normal what these brain stem
areas do is stop big movements like
kicking and arm swinging without this
kind of inhibition a person might knock
a lamp off their nightstand or bruise
themselves by kicking their footboard
but for those who share a bed this
disorder can have more serious
consequences like in 1986 when rbd was
formally identified researchers
described men who would dream they were
defending their wives from an attacker
only to wake up to find that they were
actually attacking their wives which
understandably is pretty alarming it's
the kind of thing that you do want to
treat and the very good news is that rbd
is treatable and there are two
medications research has shown to be
effective the first choice for many
doctors is clonazepam a medication
traditionally prescribed for seizures it
does come with a number of side effects
including drowsiness dizziness and
incontinence but for some that is better
than the alternative the other
medication is melatonin the same hormone
our brains secrete to make us sleepy at
night it has minimal side effects but it
only seems to work for some patients
unfortunately it's not clear right now
why these medications work but
they do seem to that being said even
though rbd is treatable it's still
something doctors tend to keep a close
eye on because sometimes this condition
can signal that something bigger is
changing in the brain earlier in this
episode i mentioned that rbd is often
associated with pre-existing
neurodegenerative diseases like
parkinson's and that's true but
researchers have also noticed another
connection here they found that many
otherwise healthy people with rbd
actually go on to develop
neurodegenerative diseases later in life
for example a 2009 study followed 93
patients who had been diagnosed with rbd
at a hospital sleep lab people who had
no other signs of neurodegenerative
disease researchers followed the health
of these patients for several years and
monitored who got diagnosed with what
and when then based on those results
they estimated the risk of developing
neurodegenerative diseases within 12
years after getting an rbd diagnosis and
that risk was a whopping 52 percent
basically a one in two chance and other
studies have found similar results
additionally papers have identified rbd
and an average of 24 of existing
parkinson's cases 88 of cases of
multiple systems atrophy and 76 of lewy
body dementia cases as for why well
these conditions are all types of alpha
synucleinopathies those are diseases
caused by buildup of the protein alpha
synuclein in where else the brainstem
the same region of the brain that causes
rbd symptoms researchers aren't exactly
sure how all of this is connected and
it's something they're still looking
into but there does seem to be a link
here between alpha synuclein and the
brainstem and rbd hopefully as we figure
it out we'll learn more about how these
diseases develop and progress for now
though rbd can at least be the canary in
the coal mine letting people know
something could be up a decade or more
before they show symptoms of full
neurodegenerative disease again not
everyone with rbd will go on to develop
these conditions but for those who do
treatments for these diseases are more
effective when they're administered
early and that counts for a lot rem
sleep behavior disorder is a reminder
that our brains are big connected
systems so the more we learn about
specific conditions the better equipped
we are to understand all kinds of other
things after all research into this rare
sleep disorder could have a lot to teach
us about some of the most common brain
diseases
so it's definitely good that we are not
acting out what our brain is cooking up
during rem sleep but during rem sleep
your brain is doing more than just
keeping your body still it's also
releasing chemicals that strengthen its
connections so that you remember things
better here's how that works
it seems like some people can regale you
with every last detail of the dream they
had last night while others can't
remember whether or not they even had a
dream no matter which camp you fall in
everybody does have dreams it's just
that some people are better at
remembering them than others and whether
or not you remember those surreal
unconscious experiences has a lot to do
with the activity in your brain and with
how well you sleep scientists still
aren't totally clear on why we dream in
the first place but they have a decent
idea of what our brains are up to when
we do we dream the most when we're in a
stage of sleep called rem rem stands for
rapid eye movement and it's a stage of
deep sleep that gets its name from the
way our eyes move back and forth while
we're in it we typically have a few rem
cycles through the night beginning
around 90 minutes after we fall asleep
and each cycle can last between a minute
and an hour even though you're sleeping
deeply during your rem cycles your brain
actually acts a lot like it does when
you're awake for instance while you're
awake there's lots of blood flowing to
the cerebral cortex the thin layer that
surrounds the largest part of your brain
which plays a role in making decisions
and thinking creatively blood is also
flowing to the limbic system a set of
structures that control your emotional
response to the things you experience
during rem sleep those same parts of the
brain are active even your heart rate
and blood pressure are similar to what
they are when you're awake so you're
having lively emotional experiences a
lot like the ones you'd have when you're
awake the main difference is that while
you're asleep your brain kindly
paralyzes you so that you don't act your
experiences out they can still feel very
real though so during rem almost
everyone is having dreams and often
vivid ones but not everyone remembers
them in part that's because some people
just have more brain activity during rem
sleep the more blood you have flowing to
the cerebral cortex the more active that
part of the brain will be more brain
activity creates more vivid dreams and
more vivid dreams tend to be more
memorable but another big reason you
either remember your dreams or don't has
to do with your levels of a hormone
called norepinephrine whether you're
awake or asleep norepinephrine helps you
remember things whenever you have an
emotionally stimulating experience your
brain releases this hormone as it rushes
through your brain it binds to the nerve
cells that help us learn new information
creating pathways between them later on
electric signals in your brain can
travel back down those pathways to help
you recall the experience you were
having when they form norepinephrine is
always present at some level while
you're awake when you fall asleep though
your norepinephrine levels drop that's
true for everyone and it's especially
true during rem cycles but from then on
the amount of norepinephrine in your
brain has a lot to do with how well you
sleep if you knock right out and don't
wake up till morning your norepinephrine
levels probably rarely rise to the point
where you start creating memories but if
you're a light sleeper you likely get a
little rise in norepinephrine every time
you stir awake and that norepinephrine
helps your brain cells create
connections that make you more likely to
form a memory of the dream you were
having so being able to remember your
dreams isn't exactly the superpower it
might seem like the truth is you
probably just don't sleep very soundly
and if you've never been great at
remembering your dreams that's not a bad
thing but if you're really curious about
the places your subconscious mind
wanders while you sleep there are things
you can do to get better at remembering
for instance right when you wake up you
can keep your eyes closed and attempt to
think back on what you've dreamt as you
gradually become more conscious since
you're slowly entering awake mode you'll
be more likely to retain the memory
that's because when you wake up abruptly
your levels of cortisol the body's
stress hormone tend to take over and
focus you on the day ahead which gets in
the way of your brain forming memories
so when you wake up more slowly you have
a better shot and then you can also do
this trick you can just drink a lot of
water before bed if you keep having to
go to the bathroom you will get the
benefit of the norepinephrine rise each
time you drag your foggy brained self
out of bed and if you do manage to
remember something from a dream you
might want to write it down before you
fall back asleep but even if you never
remember anything you can be pretty sure
that your subconscious self is still
having lively adventures while you sleep
norepinephrine is highly involved in rem
sleep and it's produced in the same part
of the brain that i mentioned when i
described rbd so all this stuff is
related to an extent but now that you
know how we remember things better after
we sleep here's brit with why
dreaming is just really weird when you
think about it when you're asleep your
brain makes up these elaborate scenarios
where you're leading a herd of talking
apples or writing robot llamas through
the jungle or something and most of the
time you have no idea it isn't real then
when you wake up you forget most of the
dream and move on with your life like
that's not strange at all there's a lot
of research into the science of dreaming
and sleep in general but dreams can be
especially important in psychology i
mean don't go reaching for those dream
interpretation books or anything but
your dreams might mean more than you
think even though everybody probably
does it scientists still aren't sure
exactly how we dream it's often
associated with rapid eye movement or
rem sleep a phase of sleep where your
brain looks as active as when you're
awake but there's evidence that we dream
in non-rem sleep too so we're still
figuring out some of the biology
involved but psychologists do have a few
theories about how our brains use dreams
and sorry sigmund freud but they aren't
all freaky sex messages in fact a lot of
our dreams are pretty boring and
according to one theory that's because
your brain uses dreams for learning and
memory consolidation in a process called
cognitive level memory reactivation the
idea is that while you dream your brain
reactivates the neurons it used to learn
information while you were awake these
kinds of dreams usually happen during
non-rem sleep in the beginning of the
night for example in a 2010 study
published in current biology
participants practiced completing a
virtual maze then either took a
90-minute nap or stayed awake during the
next round of testing those who took a
nap finished faster on average than
those who didn't but the real mvps were
the group who took a nap and dreamed
about something related to the task they
improved up to 10 times more than the
others this doesn't necessarily mean
that dreaming itself gives you a better
memory the dreams just might be a side
effect of what your brain is doing
reactivating neurons to solidify
information and encode it into long-term
memory but it might explain the more
boring dreams we have it doesn't really
explain why some of our dreams are just
flat out weird though and that's where
the contemporary theory of dreaming
comes in the idea is that your dreams
are mainly controlled by what emotions
you're feeling not what you've learned
lately if you're experiencing one really
strong emotion you'll probably have
simpler dreams like if you're feeling
overwhelmed you might dream you're being
sucked up by a tornado but if you're
feeling multiple emotions your dreams
can get more complicated and random this
theory may also help explain the
relationships psychologists have seen
between dreaming and trauma especially
in those with post-traumatic stress
disorder or ptsd frequent disruptive
nightmares are actually one of the
potential criteria for diagnosing
someone with ptsd with up to 96 of
patients reporting nightmares related to
the trauma they experience according to
the contemporary theory of dreaming
people with ptsd have nightmares because
dreaming can help us resolve traumatic
emotions by processing them in our sleep
the memories might feel less painful
when we're awake that's what the brain
is trying to do at least it's not always
successful which is why ptsd often
doesn't just go away on its own there's
also another theory the threat
simulation theory of dreaming which says
that nightmares could be your brain
preparing you for danger in the real
world according to threat simulation
theory dreams were selected for during
evolution to help us survive as opposed
to being controlled by emotions so if
you dream you're being chased by an
angry saber-toothed tiger your brain
might just be preparing you in case
you're attacked in real life the idea
matches what psychologists have seen in
studies like in a 2005 study of almost
200 children where researchers found
evidence that being exposed to danger
like violence or abuse primes our brain
to dream about dangerous scenarios even
more possibly to prepare against future
threats and based on what we know about
dreaming and trauma it makes sense that
your brain would do this i mean dreaming
is kind of like a simulator where you
can't hurt yourself the threat
simulation theory alone can't really
explain all of our dreams though and
it's possible that your brain uses
dreaming in a lot of different ways
there are also plenty of scientists who
think dreams don't have a specific
purpose at all they're just what happens
when neurons randomly fire while you
sleep so it's hard to know exactly why
you dreamed that you forgot to study for
a final and showed up without pants or
tried to ride a horse down the highway
but your brain might be trying to help
you process emotions or prepare for some
kind of threat
so your dreams could help you process
real memories or prepare for real world
dangers which suggests that there are a
lot of problems that you can use your
dreams to work through and if your
interest is piqued by the idea of
getting things done while you sleep you
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can learn stuff with skillshare while
you are awake but if you've never
learned algebra before you probably will
not be able to work through that problem
in your dreams as much as you might wish
you could here is the experimental nail
in that coffin
we've probably all done this at some
point in our lives it's the night before
a big exam and
you haven't started studying yet you'll
just have to cram as much information as
possible into your brain in one night
and hope you remember it tomorrow
wouldn't it be nice if you could just go
to sleep have a recording of everything
you need to know playing in the
background and wake up ready for the
test unfortunately for those of us who
are chronic procrastinators that doesn't
work you can't learn new information
while you sleep but it turns out that
you can boost your recall of what you
studied while you were awake the idea
that you can learn totally new
information while you sleep has been
debunked for a long time way back in
1955 researchers showed pretty
conclusively that it doesn't work
earlier studies had suggested that
people could learn new things just by
hearing them in their sleep but there
were problems with the methods used in
those studies so the team wanted to look
into it more closely using an eeg which
measures brain activity to monitor how
deeply asleep the subjects were they
found that people were only able to
remember the information played to them
if they heard it when they were in the
lighter stages of sleep the
really really light stages so light in
fact that the participants were actually
mostly awake 62 years later that study's
conclusions still stand there's no good
evidence that you can learn totally new
information in your sleep but scientists
have found that there might be a way to
boost part of the learning process that
happens during sleep sleep plays a vital
role in how you create and store
memories while you're awake you learn
all sorts of new stuff taking in facts
and experiences just from going about
your everyday life that's when your
brain encodes memories making new
connections between neurons so you can
remember it all later then when you go
to sleep your brain goes through the
consolidation phase of memory formation
scientists aren't totally sure how that
works but they think your brain turns
all that stuff you just learned into
solid long-term memories by reactivating
them and strengthening those new
connections and recent research has
found that there are ways to kind of
hack that process in a 2007 study for
example a group of neuroscientists had
people learn the locations of a bunch of
different objects while it smelled like
roses then made it smell like roses
again while they were asleep when they
woke up the subjects were better at
remembering where the objects were
compared to when they did the same task
without any smells the researchers
proposed that when the subjects smelled
roses while they slept that boosted the
memory consolidation process because
their brains associated the smell with
the memories of the object locations
basically the smell acted as a cue to
their brains to reactivate those
memories strengthening the connections
between the neurons that stored them and
stronger connections meant they had an
easier time recalling the memories when
they woke up that 2007 study was small
but later studies that tested the idea
found similar results and other research
has found that this works with more than
just odor cues you can do it with sound
too for example in a study published in
the journal of neuroscience in 2013 60
people were asked to place 72 images in
different locations on a computer screen
each time they placed an item a
corresponding sound was played so for
example if they were placing down a
picture of a cat they'd hear a meow they
were told that remembering each of these
items later on would earn them a certain
number of points half of the items had
super high point values and half were
super low but to get the most points
possible they had to remember where they
placed absolutely everything and with 72
items that wouldn't be easy after they'd
made their placements the subjects took
a 90-minute nap just about enough for
one full cycle of sleep while the people
in the experimental group were sleeping
they were played 18 of the sounds
associated with low value items the
people in the control group just slept
with white noise playing instead once
they were wide awake and trying to
remember the locations of as many items
as they could for those sweet sweet
science points the subjects mostly
remembered the ones with high point
values but the people in the
experimental group also tended to
remember the low value items the ones
they'd been reminded of while they slept
the researchers concluded that just like
in the studies on odor cues the sounds
cued the subject's brains to reactivate
the memories associated with them that
strengthened those memories so they were
better at recalling them later and again
like with odor cues other studies have
also found that sound cues can boost
your recall for example in a 2014 study
that involves 68 subjects a group of
researchers found that playing sound
cues while people were asleep helped
them learn a new language they had
people learn 120 new words and their
translations then played some of those
new words back to them while they slept
the team found that people were able to
remember about 10 percent more of the
cued words than the words they hadn't
heard while they were asleep but in a
follow-up study published the next year
the same group of researchers found that
if they played the new words and their
translations the memory boost went away
so it wasn't hearing the information
while they slept that helped to remember
it it was the sound they associated with
the memory when they heard the word and
its translation it became more than a
simple sound cue and the second word
interfered with the memory consolidation
process so the next time you're cramming
for a test you might want to try
connecting the new information with
certain sounds or smells then letting
yourself hear or smell those things
again when you go to sleep you still
might not do as well as you would have
if you've just studied properly but
hacking your memory could help you get a
few more questions right
good luck
but what if you already know algebra and
then you go to sleep well that's
actually a different story here's how
scientists got people to solve math
problems in their dreams
every night people journey to an
alternate reality filled with
hallucinations and bizarre storylines
it's called dreaming and scientists
don't know why we do it i mean it's hard
to study dreams because it's not like
you can communicate back and forth with
someone while they're asleep or at least
you couldn't until now in research
published in early 2021 scientists
figured out how to communicate with
people while they're dreaming they even
got sleeping people to solve math
problems and relay the answers and their
techniques could give us fascinating
insights into why we dream and what
happens in our minds when we sleep now
it wasn't easy to get to this point in
the past most dreaming research has
involved asking people about their
dreams after they wake up and as you
might guess that's not really reliable
in other papers scientists have
attempted to interact with sleeping
people but the results of that haven't
been very exciting either for instance
some studies have tried to influence
people's memory or behaviors by
presenting them with sounds spoken words
or smells while they slept and they did
have some success in influencing
people's ability to recall information
or learn simple tasks when they woke up
but those experiments still only
involved one-way communication the
participants weren't expected to
communicate back while they were
sleeping that's what makes the 2021
study remarkable for the first time
scientists achieved two-way
communication with dreaming participants
the key to their success was that they
focus on people experiencing lucid
dreaming during a lucid dream people
know their dreaming and have some
control over the narrative so these
researchers hypothesize that if a person
has control over their consciousness
like this they might be able to answer
questions about the dream world while
they're in it the problem is that lucid
dreaming is fairly rare only 23 percent
of people experience it once or more per
month and even if you're prone to them
you can't just summon a lucid dream
whenever you want at most you can train
your brain to increase the likelihood of
having them and researchers have
developed a few strategies for this for
instance in what's known as the reality
testing method you ask yourself
throughout the day whether or not you're
dreaming the idea is that by doing this
you'll build up a habit and become more
likely to automatically ask yourself the
same question when you're half asleep so
you may catch yourself dreaming and
become lucid unfortunately this and
other strategies aren't especially
reliable which is partly why there
hasn't been a ton of research on lucid
dreaming but in the 2021 study
researchers were able to pull it off
four laboratories from around the world
recruited 36 participants who had
previously experienced lucid dreaming
the scientists knew that people
typically have lucid dreams during the
stage of deep sleep known as rem sleep
when their bodies are paralyzed but
their eyes can move so they train
participants to communicate using eye
movements while they were awake they
taught them to signal they were having a
lucid dream by moving their eyes left
then right three times they also trained
them to use eye movements to indicate
yes no and a series of numbers then the
participants went to sleep in a lab and
attempted to bring on a lucid dream
while they dreamt the researchers asked
them questions like what is oneplus 2 or
do you like chocolate the four labs use
various methods to communicate these
questions some used spoken words or
beeping noises while others used tactile
stimuli or light that flashed morse code
and sometimes the participants were able
to interact with the researchers by
incorporating those questions into the
storyline of their lucid dreams for
example one participant was looking at a
cloudy sky in their dream and when the
researcher flashed a light the dreamer
transformed the sensation into sunlight
flashing through the clouds another
participant approached a house in their
dream and when the researcher gave her a
math problem she transformed the address
on the house into the math equation then
the dreamers relayed the answers by
moving their eyes in those predetermined
left-right patterns to indicate yes no
or the specific number not all the
participants were able to achieve lucid
dreaming or communication during the
study because again having a lucid dream
isn't that easy but six of them
correctly answered a total of 29 verbal
and math questions during their dreams
so it's a small start but this
experiment shows that contrary to
popular belief it is possible to
communicate with dreaming people plus it
shows that people are capable of pretty
complex thinking while they're asleep
like solving math problems in morse code
based on this the researchers think
people could be trained to use lucid
dreams to solve problems that require
creativity or to practice musical or
athletic skills but more than that this
technique also gives scientists a new
way to investigate questions like why we
dream and what influences the storylines
of our dreams and that could open up a
whole new world of study and a whole new
way to understand our brains
maybe all this time you could have been
taking your math tests in the middle of
a lucid dream or more likely you are
learning things while you're awake and
that is still really cool because when
you're awake you can do things like
check out our videos on our main channel
for example one called the science of
dreaming thanks so much for watching i
hope you learned some stuff
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