- My name is Matthew Walker.
I am a professor of neuroscience and psychology
at the University of California Berkeley,
and I am the author of the book, Why We Sleep.
What is dreaming and what happens?
And are there any real benefits to dreaming?
Well, to take a step back, I think it's important
to note that dreaming, essentially, is a time
when we all become flagrantly psychotic.
And before you, perhaps, dismiss that diagnosis,
I'll give you five good reasons.
Because last night when you were dreaming,
first, you started to see things which were not there,
so you were hallucinating.
Second, you believed things that couldn't possibly be true,
so, you were delusional.
Third, you became confused about time, place, and person,
so, you're suffering from disorientation.
Fourth, you had wildly fluctuating emotions like a pendulum.
Something that we call being affectively labile.
And then, how wonderful you woke up this morning
and you've forgotten most, if not all,
of that dream experience.
So, you're suffering from amnesia.
And if you were to experience any one of those
five symptoms while you were awake,
you would be seeking psychological or psychiatric treatment.
Yet, during sleep and dreaming it seems to be both
a normal biological and psychological process.
What are the functions, then, or benefits of dreaming?
Well, we know that dream sleep
which principally comes from a stage
that we call rapid eye movement sleep,
or REM sleep.
Dream sleep, actually, provides at least
two benefits for the brain.
The first is actually creativity.
Because it's during REM sleep, and dreaming specifically,
when the brain starts to collide all of the information
that you've recently learned together
with all of this back catalog of autobiographical
information that you've got stored up in the brain,
and it starts to build novel connections.
It's almost like group therapy for memories.
And through this pattern of informational alchemy at night
we create a revised mind-wide web of associations.
And you can start to divine new novel insights
into previously unsolved problems,
so that you wake up the next morning with new solutions.
And it's probably the reason that no one has
ever told you that you should stay awake on a problem.
Instead, people tell you to sleep on a problem.
And we now have good evidence that it's dream sleep
that gifts you that type of informational wisdom
rather than simply knowledge.
The second benefit of dream sleep is, essentially,
a form of overnight therapy.
It's during dream sleep where we start
to actually take the painful sting out of difficult,
even traumatic emotional experiences that we've been having.
And sleep, almost, divorces that emotional, bitter
rind from the memory experiences that
we've had during the day.
And so that we wake up the next morning
feeling better about those experiences.
So, you can think of dream sleep as emotional first aid.
And it sort of just offers this nocturnal soothing balm
that smooths those painful, stinging edges
of difficult experiences.
So, it's not time that heals all wounds,
but it's time during dream sleep that provides
you with emotional convalescence.
(soft music)