10 Feb 2019

Raising the Bar: Neuroscientist Cathy Stinear answers audience questions about the brain

From Raising the Bar
Assoc. Prof Cathy Stinear

Assoc. Prof Cathy Stinear Photo: RNZ / Paul Bushnell

Why do we dream?

According to Assoc. Prof Cathy Stinear, one reason may be that it enables us to rehearse the actions we might take when confronted by immediate or life-threatening dilemmas. That might explain the role of nightmares, which allow us to try out different responses to threats which seem very real because they are experienced in a dream state. Dreams allow us to prepare for catastrophically awful things by role-playing our responses. Part of your subconscious, she says, is actually practising so that you can feel more ready for your life.

Although nightmares happen in our own minds, they can have physical consequences. “Who’s woken up from a nightmare in a cold sweat with our heart racing?” she asks. “Most of us have at some point in our lives.”

She draws several conclusions from this physical response to the activity of the mind.

Tyrannosaurus Rex

Tyrannosaurus Rex Photo: Pixabay

“One is that your brain is really rubbish at knowing the difference between what’s real and what’s just being imagined in your head. When you’re having the crazy stressful dream, your body responds as though it’s really happening to you. Because your brain honestly can’t tell the difference.”

This reason for this? “Because your brain is a blob of tissue locked in a dark silent box. And the only reason it thinks it knows anything about the world out there is because of the way it’s processing and putting together all the electrical signals from your eyes and your ears and your skin and tastebuds.”

Lots of research has been done looking at what happens when you vividly imagine movement, and it’s clear that our brain behaves in exactly the same way as if we were really performing that movement. At least, up to a point.

“When your body is undergoing a full REM sleep dream, you paralyse yourself. Except for your eyes. Which is why it’s called REM sleep – Rapid Eye Movement sleep. Because your eyes are allowed to move, but not the rest of you.

“You’ve got this thing in your brain stem called your reticular activating system, and when you’re in that REM sleep and you’re dreaming, it turns off all the movement commands from your brain so they don’t reach your body. So that you don’t fight the Tyrannosaurus Rex in the bed. That would be a disaster. You’re going to hurt yourself. If somebody’s with you, you’re going to smash them, and they won’t appreciate it. You switch it off so you’re nice and still.”

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Photo: Pixabay

There are however some disorders where that process goes a bit wonky. “Something like Parkinson’s Disease, for example affects the function of the reticular activating system. And it gets pretty violent. But it just reminds us how important it is for our brains to turn off all those actions it is busy rehearsing.”

What happens if we don’t dream? “I think there’s a difference between not dreaming and not remembering that we’re dreaming. Lots of people don’t remember their dreams and that’s OK. But getting to that deep sleep stage where you can dream, even if you’re not remembering it, is really important for brain health, mental health, and overall wellbeing.”

About the speaker

Dr Cathy Stinear is an Associate Professor in the Department of Medicine at Auckland University. She is a clinical neuroscientist, developing tools to predict and promote recovery after stroke. She’s also part of the University’s Creative Thinking Project, where she works with researchers, artists and educators to facilitate a deeper understanding of the creative process, and promote creativity as central to individual and community wellbeing and development. 


Photo: University of Auckland

Raising the Bar was recorded in association with the University of Auckland